The first step in the identification of a mineral before any chemical tests are made should be the recognition of the physical and optical properties and occurrence of the mineral. The physical properties are discussed below.
Color: The color is fairly constant in some minerals but not in all, and commonly the color is due to pigments or impurities in the minerals.
Lustre: The lustre of a mineral is its appearance in ordinary reflected light. There are seven kinds of lustre: metallic, the lustre of metals; adamantine, that of uncut diamonds; vitreous, cut diamonds, or broken glass; resinous of the yellow resins; greasy; pearly; silky. There are five degrees of intensity of lustre recognized: splendent, shining, glistening, glimmering, dull.
Specific Gravity: An important factor in identifying a mineral is the specific gravity, or weight of the mineral in air compared with the weight of an equal volume of water. Minerals can be classed as heavy and light, thereby eliminating many of the possibilities that a specimen could be due to its other physical properties. Minerals with a specific gravity of 3.5 or more are generally considered as heavy, whereas minerals with a specific gravity of 3.2 or less are considered to be light.
Streak: The streak is more nearly constant than the color. The streak is determined by crushing the mineral, or by marking unglazed porcelain, or simply by scratching the mineral with a knife and observing the color of the powder. The color of the streak may differ considerably from the color of the mineral specimen as in the case of hematite, the streak which is always red although the color of this mineral may vary from red to black.
Hardness: The resistance to abrasion, or scratching. For convenience in description hardness is often designated by a number according to a scale devised by Mohs. This scale is as follows (talc being the softest and diamond the hardest):
- Talc
- Gypsum
- Calcite
- Fluorite
- Apatite
- Orthoclase
- Quartz
- Topaz
- Corundum
- Diamond
The approximate hardness can be easily determined by noting the ease or difficulty with which a mineral scratches or is scratched by one of the following:
- Thumbnail……………………2.5
- Quartz or flint ………………7.0
- Copper or silver coin……. 3.0
- Emery (wheel or paper)..8.0 to 9.0
- Knife blade ………………….5.5 to 6.0
- Corundum paper …………9.0
- Window glass ……………….5.5 to 6.0
- Carborundum ………………9.5
- File ……………………………..6.5 to 7.0
- Diamond ……………………..10.0
If you can scratch a mineral with a knife blade, but not with a copper or silver coin, its hardness lies between 3 and 6, etc.
Occurrence and Characteristics: Occurrence refers to the form in which it is found, other minerals with which it is associated in the deposit, and its relation to the enclosing rock. Occurrence is an extremely valuable factor in the identification of a mineral. Special Characteristics:
A) MAGNETISM: If a mineral is magnetic it may rapidly lead to the identification of the mineral. Magnetite, pyrrhotite, ilmenite, iron-platinum, and chromite may occur as a magnetic mineral.
B) SOLUBILITY: Minerals which are soluble in water may be one of the following: potash, soda, nitrates, borax, epsom salt, and halite.
C) TASTE: Soluble minerals usually have a characteristic taste.
- Potash………………..Alkaline
- Epsomite…………….Bitter-saline
- Epsom Salt………….Bitter
- Nitre…………………..Saline-cooling
- Borax………………….Sweetish-alkaline
- Sylvite…………………Bitter-saline
- Carnalite……………..Bitter
D) ODOR: Some minerals emit characteristic odors. Examples:
- Kaolinite, odor of clay, when breathed upon.
- Arsenopyrite, odor of garlic upon heating.
- Pyrite, sulfurous odor upon heating.
E) FEEL OR TOUCH: When a mineral is rubbed by the finger, it may have a characteristic feel. Examples:
- Graphite feels greasy.
- Kaolinite feels greasy.
- Meerschaum feels smooth.
- Molybdenite feels greasy.
- Talc feels greasy.
In the following table, the figures after each name of an ore indicate the percentage of the element specified which the pure mineral contains. When this is variable or is merely mechanically included, an interrogation mark takes the place of the above-mentioned figure.
Important ores are in heavy face type, less common species are in lighter type, and minerals which are only occasionally mined and treated for the element specified are in italics. Each group is arranged in the order of decreasing importance.
|
Name |
Formula | %Metal | Color | Lustre | Streak | Hardness | SG |
Characteristics Occurrence |
| ACTINOLITE | Ca(MgFe)3(SiO3)4 | No metal source | Green | Vitreous | 5.0-6.0 | 3.0-3.2 | Usually long crystals, columnar
or fibrous |
|
| ALBITE | NaAlSi3Os | Al2O3-19.5% | White to blue | Vitreous | White | 6.0-6.6 | 2.6-2.7 | Occurs with gneiss, schists, pegmatite and limestone |
| ALMANDITE | Fe3Al2(SiO4)3 | No metal source | Red to black | 6.5-7.5 | 3.1-4.3 | Accessory rock mineral; variety
of garnet |
||
| ALTAITE | PbTe | 61.9% Pb | Tin white
Yellow tinge |
Metallic | Grayish
Black |
3.0 | 8.2 | Associated with pyrite, galena,
tetrahedrite |
| ALUNITE | K2(Al2OH)6. (SO4)4 | K-9.4%.
Al-19.6% |
Pink-red | Vitreous
Pearly |
White | 3.8 | 2.7 | Associated with kaolin and pyrite |
| AMOSITE | (FeCaH2Mn)OSiO2 | No metal source | Gray to green | 2.2-2.3 | Long fibered asbestos | |||
| ANALCITE | NaAlSi2O6. 2H2O | Al2O3-23.2% | White | Vitreous | White | 5.0-5.5 | 2.2-2.3 | Common Zeolite; yields water |
| ANDALUSITE | Al2SiO5 | Al2O3-63.2% | White
Red-green |
Vitreous | 7.5 | 3.2 | Nearly square prisms; occurs with
gneiss, mica, schists |
|
| ANDRADITE | Ca3Fe2(SiO4)3 | No metal source | Green
Red-black |
Adamantine | 6.5-7.5 | 3.1-4.3 | Garnet and sometimes used as a
gem |
|
| ANGLESITE | PbSO4 | Pb-68.3% | Yellow
Green-gray |
Adamantine,
Vitreous |
White | 2.8-3.0 | 6.1-6.4 | Occurs in oxidation zones of lead
veins |
| ANORTHITE | CaAl2Si2O8 | Al2O3-36.7% | White, Gray-red | Vitreous | White | 6.0-6.5 | 2.7-2.8 | Occurs in igneous rocks |
| ANTHOPHYLLITE | (MgFe)SiO3 | No metal source | Gray
Brown-green |
Vitreous | Uncolored,
Grayish |
5.0 | 3.2-3.2 | Found in crystalline schists |
| APATITE | Ca4(CaF) (PO4)3 | P2O5-42.3% | Green-blue | Vitreous | White | 4.5-5.0 | 3.2 | Granular; frequently massive;
common in metamorphic rocks |
| ARAGONITE | CaCO3 | CaO-56% | White | Vitreous | White | 3.5-4.0 | 2.9 | Found in beds of iron ore and
gypsum |
| ARGENTITE | Ag2S | Ag-87.1% | Black | Metallic | Shiny Black | 2.0-2.5 | 7.2-7.4 | Cuts like lead; with silver, cobalt and nickel |
| ARGYRODITE | 3Ag2S.GeS2 | Ag-73.5% | Steel gray red tinge | Metallic | Grayish Black | 2.5 | 6.1 | Occurs with sphalerite, siderite and marcasite |
| ARSENOPYRITE | FeAsS | Fe-34.3%
As-46.0% |
Steel Gray | Metallic | Gray, Black | 5.5-6.0 | 5.9-6.3 | Widely spread; yields sparks and
garlic odor when struck |
| ATACAMITE | Cu2(OH)3Cl | Cu-59.5% | Green | Adamantine,
Vitreous |
Apple Green | 3.0-3.5 | 3.8 | Always of secondary origin with
copper ores |
| AZURITE | 2CuCo3.Cu(OH)2 | Cu-55.0% | Blue | Vitreous, Dull | Blue | 3.5-4.0 | 3.8-3.9 | Occurs with other copper minerals |
| BARITE | BaSO4 | BaO-65.7% | White, Blue-red | Vitreous | White | 2.5-3.5 | 4.3-4.6 | Found commonly as gangue of
lead-zinc ores |
| BAUXITE | Al2O3.3H2O | Al-34.9% | White-red
Brown-yellow |
Dull | Like Color | 1.0-3.0 | 2.6 | Chief ore of aluminum, occurs
massive |
| BENTONITE | (CaMg)O, SiO2 (AlFe)2O3 | No metal source | Blue | 1.0 | 2.1 | The clay of montmorillonite | ||
| BERYL | Be3Al2(SiO3)6 | Be—5%
Al2O3-19% |
White, Green-blue | Vitreous | White | 7.5-8.0 | 2.6-2.8 | Often imbedded in quartz; with
mica, feldspar |
| BERYLLONITE | NaBePO4 | Be-7.1% | White-yellow | Vitreous,
Brilliant |
5.8 | 2.8 | Found with beryl, feldspar, columbite | |
| BIOTITE | (HK)2(MgFe)2Al2(SiO4)3 | No metal source | Black-Brown | Pearly,
Vitreous |
White | 2.5-3.0 | 2.7-3.1 | Perfect cleavage into very thin
leaves |
| BISMITE | Bi2O3 | No metal source | Straw Yellow
White |
Pearly | 4.4 | Of secondary origin resulting
from oxidation |
||
| BISMUTH | Bi | Bi-100% | Silver White | Metallic | Silver White | 2.3 | 9.7 | Native; with cobalt, nickel; brassy
tarnish |
| BISMUTHINITE | Bi2S3 | Bi-81.2% | Lead gray | Metallic | Like Color | 2.0 | 6.4-6.5 | Occurs in form of thin coating |
| BISMUTITE | (BiO)2.CO3.H2O | No metal source | Green-white | 4.0 | 6.9-7.7 | Incrusting fibrous, or earthy and
pulverulent |
||
| BORAX | Na2B4O7.10 H2O | B2O3-36.6%
Na2O-16.2% |
White | Vitreous, Dull | White | 2.0-2.5 | 1.7 | Refer to introduction for characteristic taste |
| BORNITE | Cu3FeS4 | Cu-63.3% | Reddish | Metallic | Blackish Gray | 3.0-3.5 | 4.9-5.4 | Associated with chalcocite; massive |
| BOURNONITE | 3(PbCu2)S.Sb2S3 | Pb-24.7%
Cu-42.5% |
Steel gray
Iron black |
Metallic | Like Color | 2.5-3.0 | 5.7-5.9 | Occurs fine grained massive; brittle |
| BRAUNITE | 3Mn2O3.MnSiO3 | Mn-78.3% | Steel gray
Brownish black |
Submetallic | Like Color | 6.0-6.5 | 4.8 | Occurs in porphyry; brittle |
| BREITHAUPTITE | NiSb | Ni-32.5%
Sb-67.5% |
Copper red | Metallic | Reddish
Brown |
5.5 | 7.5 | Occurs with other sulfides and
silver minerals |
| BROCHANTITE | CuSO4.3Cu(OH)2 | Cu-56.2% | Green | Vitreous | Green | 3.5-4.0 | 3.9 | Found in oxidation zones of copper deposits |
| BRUCITE | MgO.H2O | MgO-69% | White to gray
blue, green |
Pearly,
Vitreous |
White | 2.5 | 2.4 | Associated with serpentine; secondary mineral |
| CALAMINE | AuTe2 | Au-43.6% | Bronze yellow
Silver-yellow tinge |
Yellowish
Gray |
2.5 | 9.0 | Similar to sylvanite, krennerite | |
| CALAVERITE | CaCO3 | CaO-56% | Many colors | Vitreous | White | 3.0 | 2.7 | Transparent to opaque; many
varieties |
| CALOMEL | HgCl | Hg-85%
Cl-15% |
White, yellow | Adamantine | Pale Yellow,
White |
1.0-2.0 | 6.5 | Associated with cinnabar |
| CARNALLITE | KMgCl3.6H2O | K-14.1%
Cl-38.3% |
White | Shining | 2.5 | 1.6 | Strongly phosphorescent; taste-bitter | |
| CARNOTITE | K2O.2U2O3.V2O3.3H2O Variable | Variable | Yellow | Vitreous, Dull | Yellow | 1.5 | Mixed with sands; yellow crystal
line powder |
|
| CASSITERITE | SnO2 | Sn-78.8% | Brown,black,
red |
Adamantine | White, Light
Brown |
6.0-7.0 | 6.8-7.1 | The source of tin; opaque to
translucent |
| CELESTITE | SrSO4 | Sr-47.7% | Light blue,
white, red |
Vitreous | White | 3.0-3.5 | 3.9-4.0 | Often associated with sulphur; in
beds of limestone |
| CERARGYRITE | AgCl | Ag-75.3% | Pearly gray | Waxy, greasy | White to
Gray |
1.0-1.5 | 5.6 | Cuts like wax; exposure changes
color to violet brown |
| CERUSSITE | PbCO3 | Pb-77.5% | White, gray | Adamantine | White | 3.0-3.5 | 6.5-6.6 | Specific gravity important; with
lead ores |
| CERVANTITE | 2Sb2O4 Sb2O3. Sb2O3 | Sb-79.4% | Yellow
reddish white |
Greasy, Pearly | White | 4.0-5.0 | 4.1-5.3 | Usually associated with stibnite |
| CHALCANTHITE | CuSO4.5H2O | CuO-31.8% | Blue | Vitreous | White | 2.5 | 2.1-2.3 | Formed by oxidation of copper
sulphides |
| CHALCEDONY | SiO2 | No metal source | Pale blue, gray
White to black |
Waxy | White | 7.0 | 2.6-2.7 | Often contains some disseminated
opal-silica |
| CHALCOCITE | Cu2S | Cu-79.8% | Black-Gray | Metallic | Like Color | 2.5-3.0 | 5.5-5.8 | Highly polished surface where cut |
| CHALCOMENITE | CuSeO3.2H2O | Cu-28.1%
Se-34.9% |
Blue | Vitreous | 2.5-3.0 | 3.8 | With various selenides of silver copper, and lead | |
| CHALCOPYRITE | CuFeS2 | Cu-34.6% | Brassy yellow | Metallic | Greenish
Black |
3.5-4.0 | 4.1-4.3 | Softer than pyrite; with pyrite,
galena, sphalerite |
| CHERT | SiO2 | No metal source | White-gray | 7.0 | 2.6 | Impure, coarse-grained, opaque
flint |
||
| CHLOANTHITE | NiAs2 Variable | NI-28.1%
As-71.9% |
Tin white,
steel gray |
Metallic | Grayish black | 5.8 | 6.5 | Associated with smaltite, cobalt,
silver and copper |
| CHROMITE | FeO.Cr2O3 | Cr-46.2% | Black | Vitreous | Dark Brown | 5.5 | 4.3-4.6 | Usually associated with serpentine; brittle |
| CHRYSOBERYL | BeOAl2O3 | BeO-19.8% | Green | Vitreous | White | 8.5 | 3.7-3.8 | Resembling green glass; brittle |
| CHRYSOCOLLA | CuOSiO2.2H2O | Cu-36.2% | Blue, green | Vitreous, Dull | White | 2.0-4.0 | 2.0-2.2 | Adheres to dry tongue; important ore of copper |
| CHRYSOLITE | (MgFe)2SiO4 | No metal source | Green | Vitreous | White or
Yellowish |
6.5-7.0 | 3.3 | Occurs in granular masses; brittle |
| CHRYSOTILE | H4Mg3Si2O9 | White, greenish | Metallic | White | 1.7 | 2.2 | Fibered asbestos; parallel fibers | |
| CINNABAR | HgS | Hg-86.2% | Red | Adamantine,
Submetallic |
Scarlet | 2.0-2.5 | 8.0-8.2 | Only important ore of mercury;
tastes “chalky” |
| CLAUSTHALITE | PbSe | Pb-72.4% | Lead gray | Metallic | Lead gray | 2.8 | 8.0 | Resembles granular galena |
| COBALTITE | CoAsS | Co-35.5% | Tin white,
steel gray |
Metallic | Grayish Black | 5.5 | 6.0-6.3 | Occurs commonly granular; ore
of cobalt |
| COLEMANITE | Ca2B6O11.5H2O | No metal source | White,
yellowish |
Brilliant,
Vitreous |
White | 4.0-4.5 | 2.4 | Usually occurs as geodes; brittle |
| COLUMBITE | (FeMn)(CbTa)2O6 | Variable-Ta2O5
3.3 to 31.5% |
Iron black | Submetallic | Dark Red,
Black. |
6.0 | 6.3 | Brittle; nearly pure niobate |
| COPPER | Cu | Cu-100% | Copper red | Metallic | Copper red | 2.8 | 8.8 | Tarnishes easily; malleable |
| CORUNDUM | Al2O3 | AI-52.9% | All colors | Vitreous,
Adamantine |
White | 9.0 | 3.9-4.1 | Brittle; very tough when compact |
| COSALITE | Pb2Bi2S6 | Pb-41.8%
Bi-42.1% |
Lead gray | Metallic | Black | 2.8 | 6.5 | In quartz veins; with pyrite,
sphalerite |
| COVELLITE | CuS | Cu-66.5% | Blue | Submetallic | Black | 1.5-2.0 | 4.6 | Opaque, turns blue when moistened |
| CROCIDOLITE | NaFe(SiO3)2.FeSiO3 | No metal source | Blue to green | Silky, Dull | Like Color | 4.0-5.0 | 3.2-3.3 | Fibrous masses; like asbestos,
valuable |
| CROCOITE | PbCrO4 | Pb-64.1%
Cr-16.1% |
Red | Adamantine | Orange
Yellow |
2.5 | 6.0 | Found with quartz, galena, vanadinite |
| CRYOLITE | Na3AlF6 | Al-13%
F-54.4% |
Snow white | Greasy to
Vitreous |
White | 2.5 | 3.0 | Appearance, hardness are distinctive |
| CUPRITE | Cu2O | Cu-88.8% | Red | Adamantine
to dull |
Red | 3.5-4.0 | 5.9-6.2 | Brittle; transparent to opaque;
fine grained |
| CYANITE | Al2SiO5 | Al-33.3% | White, to blue
or green |
Vitreous,
Pearly |
5.0-7.0 | 3.6 | Long, bladed triclinic crystals;
sometimes fibrous |
|
| DESCLOIZITE | 4RO.V2O5.H2O | Variable. V2O5 | Red, brown, black | Greasy | Orange | 3.5 | 6.0 | Associated with vanadinite |
| DIAMOND | C | C-100% | White, gray | Adamantine,
Greasy |
Ash Gray | 10.0 | 3.5 | Found with serpentine, placers,
magnetite, gold |
| DIASPORE | Al2O3. H2O | Al2O3-85% | Many colors | Vitreous | White | 6.5-7.0 | 3.4 | Occurs in thin scales; very brittle |
| DIATOMACEOUS
EARTH |
SiO2.n H2O | Yellow to brown | Vitreous | White to
Gray |
2.0 | 2.2 | Siliceous; scratches glass; light
In weight |
|
| DOLOMITE | CaMg (CO3)2 | CaO-30.4%
MgO-21.9% |
White, gray,
pink, yellow |
Vitreous,
Pearly |
White | 3.5-4.0 | 2.8-2.9 | Effervesces vigorously with hydrochloric acid |
| ENARGITE | 3CU2S. AS2S5 | Cu-48.4% | Iron black | Metallic | Black | 3.0 | 4.4 | Color and streak both black;
prismatic cleavage |
| EPIDOTE | Ca2(Al0H)(AlFe)2
(SiO4)3 |
No metal source | Green | Vitreous, Dull | White | 6.0-7.0 | 3.2-3.5 | Brittle; usually granular |
| EPSOM SALT | MgSO4.7 H2O | Mg-9.9% | White | Vitreous | White | 2.3 | 1.7 | Tastes bitter and saline; in mineral waters |
| ERYTHRITE | CO3AS2O8.8H2O | Co-29.5% | Crimson, gray | Pearly | Paler than
Color |
1.5-2.5 | 3.0 | Deposits of secondary origin;
with cobalt ores |
| FERBERITE | FeWO4 | W-60.6% | Brown, black | Metallic | 5.0-5.5 | 7.2-7.5 | Found with other tungsten ores | |
| FLUORITE | CaF2 | F-48.9% | All colors | Vitreous | White | 4.0 | 3.0-3.3 | Octahedral cleavage; brittle |
| FRANKEINITE | (ZnFeMn)O
(FeMn)2O3 |
Zn-14.2%
Mn-35.7% |
Iron black | Metallic | Brown to
Black |
5.5-6.5 | 5.2 | Usually associated with zincite;
sometimes magnetic |
| GALENA | PbS | Pb-86.6% | Lead gray | Metallic | Lead Gray | 3.0 | 7.4-7.6 | Very brittle; cubic cleavage |
| GARNET | Various | No metal source | Red, brown,
yellow |
Vitreous | White | 6.5-7.5 | 3.2-4.3 | Usually imbedded in mica or
other schists |
| GARNIERITE | H2(NiMg)SiO4 | Ni-25% to 30% | Green | Dull, greasy | Greenish.
White |
2.0-4.0 | 2.4 | Amorphous; source of nickel;
with serpentine, chromite |
| GENTHITE | 2NiO,2MgO.
3SiO2.6 H2O |
Ni-22.6% | Green | Dull, greasy | Greenish.
White |
2.0-4.0 | 2.4 | Similar to garnierite |
| GIBBSITE | Al(0H)3 | Al-34.6% | White, green | Pearly | 2.0-3.5 | 2.4 | Occurs under same conditions as
bauxite |
|
| GOLD | Au | Au-100% | Golden | Metallic | Golden
Yellow |
2.8 | 15.6-19.3 | Malleable; does not famish;
many associations |
| GRAPHITE | C | C-100% | Black | Dull,
Submetallic |
Dark Gray,
Iron Black |
1.0-2.0 | 2.2 | Soft; marks paper; feels greasy;
often impure |
| GREENOCKITE | CdS | Cd-77.7% | Yellow | Adamantine | Yellow to red | 3.0-3.5 | 5.0 | Usually occurs as coating on zinc
minerals |
| GROSSULARITE | Ca3Al2(SiO4)3 | No metal source | White, green,
yellow |
Vitreous | White | 6.5-7.5 | 3.4-3.7 | Often imbedded in mica and
schists; limestones |
| GYPSUM | CaSO4.2H2O | CaO-32.6% | White, red | Vitreous | White to
Gray |
1.5-2.0 | 2.3 | In limestones, shales; monoclinic
crystals |
| HALITE | NaCl | Na-39.4% | White | Vitreous | White | 2.5 | 2.1-2.6 | Taste-saline. Important source of
sodium |
| HALLOYSITE | H4Al2O3.2SiO2.H2O | No metal source | White, green,
blue, red |
Pearly, Waxy,
dull |
1.0-2.0 | 2.0-2.2 | Often occurs in veins of ore as
secondary product |
|
| HAUSMANNITE | Mn3O4 | Mn-72% | Black,brown | Metallic | Brown | 5.3 | 4.7 | Associated with other manganese
minerals |
| HEMATITE | Fe2O3 | Fe-70% | Brown, red, black | Metallic, Dull
Submetallic |
Red, Brown | 5.5-6.5 | 4.9-5.3 | Becomes magnetic upon heating
under reducing conditions |
| HESSITE | Ag2Te | Ag-63% | Gray | Metallic | Black | 2.5-3.0 | 8.3-8.9 | With chalcopyrite, pyrite, and
sphalerite |
| HORNEBLENDE | Variable | Variable | White, green,
black |
Vitreous | 5.0-6.0 | 3.2 | Many varieties; one of the amphiboles | |
| HUEBNERITE | MnWO4 | Mn-18.1%
W-60.7% |
Brown | Submetallic | Yellowish
Brown |
5.0-5.5 | 7.2-7.5 | Occurs with other tungsten minerals and galena |
| HYDROZINCITE | ZnCo3.2Zn(OH)2 | Zn-59.5% | White, gray,
yellow |
Dull | White | 2.0-2.5 | 3.6-3.8 | Usually associated with other
zinc ores |
| HYPERSTHENE | (FeMg)SiO3 | No metal source | Black | Pearly | Gray | 5.0-6.0 | 3.5 | Occurs in foliated or platy masses |
| ILMENITE | FeTiO3 | Ti-31.6% | Iron black | Metallic,
Submetallic |
Brown | 5.0-6.0 | 4.5-5.0 | Magnetic; with pyrite, horneblende,
feldspars |
| IODYRITE | Agl | Ag-46% | Yellow, green | 3.0-4.0 | 5.6-5.7 | Usually in thin plates; rare | ||
| IRIDIUM | Variable | Variable | White | Metallic | 6.7 | 22.7 | With platinum and allied metals | |
| IRIDOSMENE | IrOs(RhPtRu | Alloy-100% | Tin White | Metallic | 6.0-7.0 | 19.3-21.1 | Rare metals alloy | |
| JAMESONITE | 2PbS.Sb2S3 | Pb-50.8%
Sb-29.5% |
Gray | Metallic | Grayish
Black |
2.0-3.0 | 5.5-6.0 | Usually associated with quartz;
brittle |
| JEFFERISITE | Variable | Variable. | Yellowish brown | Pearly | White | 1.5 | 2.3 | Mica loosely combined with water; with serpentine |
| KAINITE | MgSO4.KCl.3H2O | KCl-30.0% | White to red | Vitreous | 2.8 | 2.1 | Found in granular masses; with
halite, sylvite |
|
| KAOLINITE | H4Al2Si2O9 | Al2O3-39.5% | White, yellow | Pearly | Same as Color | 2.0-2.5 | 2.6 | Widespread; earthy odor; clay |
| KERMESITE | Sb2S2O | Sb-75.3% | Cherry | Adamantine,
Metallic |
Brownish
Red |
1.3 | 4.6 | Occurs with stibnite |
| KIESERITE | MgSO4.H2O | Mg-17.6% | White, yellow | Vitreous | 3.3 | 2.6 | Often with gypsum and carnallite | |
| LEPIDOLITE | KLi[Al(OHF) 2]
Al(SiO3)3 |
Small amount
of Li |
Red, lilac, white | Pearly | White | 3.0 | 2.8-3.3 | Occurs in granite, gneiss; with
muscovite |
| LEUCITE | KAI(SiO3)2 | K2O-21.5%
Al2O3-23.5% |
Gray | Vitreous, Dull | White | 5.5-6.0 | 2.5 | Occurs only in igneous rocks,
particularly recent lava flows |
| LIMESTONES | Chiefly CaCO3 | Ca-40% | Variable | Dull | White | 3.0 | 2.7 | Widely distributed; large deposits |
| LIMONITE | 2Fe2O3-3H2O | Fe-59.9% | Brown, yellow | Submetallic | Yellowish
Brown |
5.0-5.5 | 3.6-4.0 | Massive, fibrous or porous; magnetic after fusing |
| LINNAEITE | CO3S4 | Co-58.0% | Steel gray | Metallic | Blackish
Gray |
5.5 | 4.8-5.0 | Copper red tarnish; in gneiss
with chalcopyrite |
| LIYINGSTONITE | HgS.2Sb2S3 | Hg-22.0% | Lead gray | Metallic | Red | 2 | 4.81 | Resembles stibnite; fuses easily |
| MAGNESITE | MgCO3 | Mg-28.9% | White to black | Vitreous | White | 4.0-4.5 | 3.1 | Often associated with serpentine;
chalk-like |
| MAGNETITE | FeO.Fe2O3 | Fe-72.4% | Iron black | Metallic,
Submetallic |
Black | 5.5-6.5 | 5.2 | Strongly magnetic; many associations |
| MALACHITE | CuCO3.Cu(OH)2 | Cu-57.5% | Green | Silky | Green | 3.5-4.0 | 4.0 | Usually associated with other
copper minerals |
| MANGANITE | Mn2O3.H2O | Mn-62.5% | Iron black,
steel gray |
Metallic,
Submetallic |
Brown | 4.0 | 4.2-4.4 | Hardness and streak are distinctive |
| MARBLE | Chiefly CaCO3 | Ca-40% | Variable | Vitreous,
Earthy |
White, Gray | 3.0 | 2.7 | Varieties based on accidental Impurities |
| MARCASITE | FeS2 | Fe-46.6% | Yellow | Metallic | Grayish,
Brown, black |
6.0-6.5 | 4.9 | Same uses as pyrite; brittle |
| MARMATITE | (ZnFe)S Variable | Zn-46.5%
to 56.9% |
Yellow, brown,
black |
Adamantine | Brownish | 5.0 | 3.9-4.2 | Closely allied with galena; common zinc ore |
| MEUCONITE | CuO | Cu-79.9% | Black | Earthy,
Metallic. |
3.0-4.0 | 6.5 | Sublimation product in volcanic
regions |
|
| MELILITE | Ca12Al4Si9O36 | White, yellow,
green, brown |
Vitreous | 5 | 2.9-3.1 | Formed from magmas; common
in Portland cement |
||
| MERCURY | Hg | Hg-100% | Tin white | Metallic | 13.59 | Liquid; rarely found in metallic
state |
||
| METACINNABARITE | HgS | Hg-86.2% | Grayish black | Metallic | Black | 3 | 7.7 | Found in upper portions of mercury deposits |
| MILLERITE | NiS | Ni-64.8% | Yellow | Metallic | Greenish
Black |
3.0-3.5 | 5.3-5.7 | Valuable ore of nickel; needle
like crystals |
| MIMETITE | (PbCl)Pb4AS3O12 | Pb-69.7% | Yellow to brown | Resinous | White | 3.5 | 7.0-7.3 | A minor ore of lead; uncommon
species |
| MOLYBDENITE | MoS2 | Mo-60% | Lead gray | Metallic | Greenish Gray | 1.0-1.5 | 4.7-4.8 | Greasy; makes dark greenish
mark on glazed paper |
| MOLYBDITE | MoO3 | Mo-66.67% | Yellow | Adamantine,
Pearly |
1.5 | 4.5 | Occurs with molybdenite | |
| MONAZITE | (CeLaDy)PO4.ThSiO4 | ThO2-9% | Yellow, brown | Resinous | White | 5.0-5.5 | 4.9-5.3 | Rounded grains; with gold,
chromite, iron |
| MOTTRAMITE | Variable | Variable | Black, yellow | Resinous | Yellow | 3 | 5.8 | A vanadate of lead and copper |
| MUSCOVITE | H2KAl3(SiO4)2 | Variable | Yellowish white | Vitreous,
Pearly |
White | 2.0-2.5 | 2.8-3.0 | Perfect cleavage into very thin
leaves |
| NAUMANNITE | (Ag2Pb)Se | Ag-43.0% | Iron black | Metallic | Iron Black | 2.5 | 8 | Malleable; in cubic crystals; selenide
of silver and lead |
| NEPHELITE | NaAlSiO4 | No metal source | White, yellow | Vitreous,
Greasy |
White | 5.5-6.0 | 2.5-2.7 | Widely distributed in igneous
rocks; usually massive |
| NICCOLITE | NiAs | Ni-44.1%
As-55.9% |
Copper red | Metallic | Brownish
Black |
5.0-5.5 | 7.3-7.7 | Often found with a green coating; brittle; compact |
| NITRE | KNO3 | K-38.6%
N-13.9% |
White | Vitreous | White | 2 | 2.1 | Tastes saline and cooling; salt
petre |
| OLIVINE | (MgFe)2.SiO4 | No metal source | Green | Vitreous | White or
Yellowish |
6.5-7.0 | 3.3 | Occurs in granular masses; brittle |
| OPAL | SiO2.nH2O | No metal source | All colors | Greasy,
Vitreous |
White | 5.5-6.5 | 1.9-2.3 | Amorphous silica; very smooth |
| ORPIMENT | AS2S3 | As-61% | Lemon yellow | Resinous | Lemon
Yellow |
1.5-2.0 | 3.5 | Usually associated with realgar;
seldom valuable |
| ORTHOCLASE | KAlSi3O8 | Al2O3-18.4% | Red, gray,
yellow, white |
Vitreous, Dull | White | 6.0-6.5 | 2.5-2.6 | Common constituent of igneous
rocks; most common of all silicates |
| PENTLANDITE | (FeNi)S | Fe-42.0%
Ni-22.0% |
Yellow-bronze | Metallic | Black | 3.5-4.0 | 4.6-5.0 | Associated with pyrrhotite, millerite,
chalcopyrite, etc. |
| PETZITE | (AuAg)2 Te | Au-25.5%
Ag-42% |
Gray to black | Metallic | Gray | 2.5 | 9.1 | A rare but valuable ore of gold
and silver; often tarnishes |
| PHOSPHATE ROCK | Ca3(PO4)2 | P2O5-32.1% | Gray | Dull | Gray | 5 | 3.2 | Occurs in massive deposits |
| PLATINUM | Pt | Pt-100% | Tin white,
steel white |
Metallic | Shiny Gray | 4.5 | 17.0 | Sometimes magnetic; with gold
and chromite |
| POLIANITE | MnO2 | Mn-63.2% | Steel gray,
iron gray |
Metallic | Black | 6.3 | 4.9 | Looks like pyrolusite, but harder
and dryer; rare |
| POLYBASITE | 9Ag2S.Sb2S3 | Ag-75.6%
Sb-9.4% |
Iron black | Metallic | Black | 2.0-3.0 | 6.0-6.2 | With chalcopyrite, calcite, pyrargyrite, stephanite |
| POWELLITE | Ca(Mo,W)O4 | Variable | Greenish yellow | Resinous | 3.5 | 4.5 | Often associated with scheelite | |
| PROUSTITE | 3Ag2S.As2S3 | Ag-65.5% | Scarlet | Adamantine,
Dull |
Scarlet | 2.0-2.5 | 5.6 | Usually associated with other silver ores |
| PSILOMELANE | MnO2.H2O.K2.BaO2 | Black | Submetallic
Dull |
Black,
Brownish Black |
5.0-6.0 | 3.7-4.7 | Hardness and appearance distinctive; with pyrolusite | |
| PYRARGYRITE | 3Ag2S.Sb2S3 | Ag-60%
Sb-22.2% |
Black, reddish | Adamantine,
Metallic |
Purplish Red | 2.5 | 5.8-5.9 | Often associated with argentite
and proustite |
| PYRITE | FeS2 | Fe-46.7% | Brass yellow | Metallic | Greenish
Brn.-Blk. |
6.0-6.5 | 5.0 | In all types of rock; used in
manufacture of H2SO4 |
| PYROLUSITE | MnO2 | Mn-63.2% | Black, dark gray | Metallic, Dull | Black,
Blu.-Blk |
1.0-2.5 | 4.8 | Soils fingers; hardness and streak
are distinctive |
| PYROMORPHITE | Pb3Cl(PO4)3 | Pb-76.4% | Yellow | Greasy,
Adamantine |
White,
Yel.-White |
3.5-4.0 | 5.9-7.1 | Alteration product of lead minerals |
| PYROPE | Mg3Al2(SiO4) 3 | No metal source | Red | Vitreous,
Resinous |
6.5-7.6 | 3.7 | If transparent, then prized as a
gem. Precious garnet. |
|
| PYROPHYLLITE | HAI(SiO3)2 | Al2O3-28.3% | White, brown | Pearly, Dull | White | 1.0-2.0 | 2.8-2.9 | Feels greasy or soapy |
| PYROXENE | Ca(AlMgMnFe)
(SiO3)2 |
No metal source | Green | Vitreous, Dull | White to
Green |
5.0-6.0 | 3.3 | Commonly in igneous rocks;
particularly volcanic |
| PYRRHOTITE | Fe5S6 to Fe16S17 | Fe-61.5%
Variable |
Brownish yellow | Metallic | Grayish Black | 3.5-4.6 | 4.6 | Only magnetic sulphide and
therefore distinctive |
| QUARTZ | SiO2 | Si-46.9% | Colorless,
all colors |
Vitreous | White | 7.0 | 2.65-2.66 | Different colors and varieties due
to impurities |
| REALGAR | AsS | As-70.1% | Orange | Resinous | Orange | 1.5-2.0 | 2.6 | Usually associated with Orpiment;
flexible |
| RHODOCHROSITE | MnCo3 | MnO-61.7% | Usually red | Vitreous,
Pearly |
White | 3.5-4.5 | 3.5-3.6 | Becomes darker upon exposure;
an ore of manganese |
| RHODONITE | MnSiO3 | Mn-42.0% | Brownish red | Vitreous, Dull | White | 5.5-6.5 | 3.4-3.7 | With calcite, Zincite, tetrahedrite |
| ROSCOELITE | H8K(MgFe)(AIV)4
(SiO3)12 |
Variable | Brown | Pearly | Soft | 2.9 | Vanadium mica in which vanadium replaced aluminum | |
| RUBY | Al2O3 | Al-52.9% | Many colors | Adamantine,
Vitreous |
9.0 | 4.0 | Brittle; when compact very
tough; variety of corundum |
|
| RUTILE | TiO2 | Ti-60% | Brown, red,
black |
Adamantine,
Submetallic |
Light
Brown |
6.0-6.5 | 4.2 | Frequently associated with iron |
| SCHEELITE | CaWO4 | W-63.9% | White-Yellowish | Vitreous,
Adamantine |
White | 4.5-5.0 | 5.9-6.1 | Brittle; important ore of tungsten |
| SENARMONTITE | Sb2O3 | Sb-83.6% | Colorless, grayish | Vitreous, Dull | 2 | 5.3 | Formed by oxidation of stibnite | |
| SERPENTINE | H4Mg3Si2O2 | Mg-43% | Green, blackish
or yellow, white |
Wax-like,
Silky |
White | 4.0 | 2.5-2.6 | Feels smooth and sometimes
slightly greasy |
| SIDERITE | FeCO3 | Fe-48.3% | Brown, gray | Vitreous,
Pearly, Dull |
White to
Yellow |
3.5-4.0 | 3.9 | Magnetic upon heating; an ore
of iron |
| SILVER | Ag | Ag-100% | Silver white | Metallic | Silver-
White |
2.8 | 10.5 | Tarnishes easily; with gold, copper. etc. |
| SMALTITE | CoAS2 | Co-28.2%.
As-71.8% |
Tin white,
steel gray |
Metallic | Grayish Black | 5.5-6.0 | 5.7-6.8 | Occurs usually in veins with cobalt-nickel ores |
| SMITHSONITE | ZnO.CO2 | Zn-52% | Green, gray, blue | Vitreous, Dull | White, grayish | 5.0 | 4.3-4.5 | With sphalerite and calamine |
| SODA NITRE | NaNO3 | White, reddish
brown; colorless |
Vitreous | White | 1.8 | 2.3 | Taste-cooling; incrustations in
beds; massive |
|
| SPERRYLITE | PtAS2 | Pt-56.6%
As-43.4% |
Tin white | Metallic,
Brilliant |
Black | 6.5 | 10.6 | Found with gold-quartz, covellite,
limonite |
| SPESSARTITE | Mn3Al2(SiO4) 3 | No metal source | Purplish, red | Vitreous | 3.5-4.0 | 3.9-4.1 | Often associated with galena,
chalcopyrite |
|
| SPHALERITE | ZnS | Zn-67.1% | Brown, yellow,
reddish |
Submetallic,
Resinous |
Light Brown,
Yellow |
8.0 | 3.5-4.1 | Occurs in igneous rocks; often
contact mineral |
| SPINEL | MgOAl2O3 | Al2O3-71.8%
MgO-28.2% |
Yellowish,
gray, brown. |
Vitreous, Dull | White to
Gray |
6.5-7.0 | 3.1-3.2 | Occurs in granite rocks; with lepidolite |
| SPODUMENE | LiAl(SiO3)2 | Al2O3-27.4%
Li2O-8.4% |
White, grayish | Vitreous, Dull | White | 4.0 | 4.5 | Has appearance of bronze |
| STANNITE | Cu2S.FeS.SnS2 | Sn-27.5%
Cu-29.5% |
Steel gray,
iron black |
Metallic | Blackish | 2.0-2.5 | 6.2-6.3 | Associated with other silver ores |
| STEPHANITE | 5Ag2S.Sb2S3 | Ag-68.5% | Iron black | Metallic | Iron Black | 2.0-2.5 | 6.2-6.3 | Associated with other silver ores |
| STIBNITE | Sb2S3 | Sb-71.8% | Lead gray | Metallic | Lead Gray,
Black |
2.0 | 4.5-4.6 | Tarnishes black; with gold-quartz,
galena |
| STRONTIANITE | SrCO3 | Sr-59.3% | Yellow to brown
Green |
Vitreous,
Greasy |
White to.
Gray |
3.5-4.0 | 3.7 | Like aragonite in structure; in
dependent beds |
| SULFUR | S | S-100% | Yellow | Greasy,
Adamantine |
Pale Yellow | 2.0 | 2.0 | With celestite, clay, aragonite,
gypsum |
| SYLVANITE | (AuAg)Te2 | Au-24.5%
Ag-13.4% |
White to steel gray | Metallic | Same as
Color |
1.5-2.0 | 7.9-8.3 | Telluride of gold and silver |
| SYLVITE | KCl | K-52.4% | White,
yellowish red |
Vitreous | White | 2.0 | 1.98 | Taste-saline; soluble; bitter |
| TALC | H2Mg3(SiO3)4 | Mg-19.2%
Si-29.6% |
Green to white | Pearly | White | 1.0-1.5 | 2.7-2.8 | Common; feels greasy; extensive
beds |
| TANTALITE | FeTa2O6 | Variable
Ta2O6-65.6% |
Iron black | Submetallic,
Greasy, Dull |
Reddish
Brown |
6.3 | 5.3-7.3 | Iron and manganese content variable; with columbite |
| TENNANTITE | Cu8As2S7
Variable |
Cu-57.5%
Variable |
Steel gray,
iron black |
Metallic | Black, Reddish Brown | 3.0-4.5 | 4.4-4.5 | With chalcopyrite, sphalerite,
galena, tetrahedrite |
| TENORITE | CuO | Cu-79.9% | Black | Metallic | 3.0 | 5.8-6.3 | Sublimation product in volcanic
regions |
|
| TEPHROITE | Mn2SiO4 | No metal source | Red, ash gray | Vitreous | 6.5-7.0 | 4.0-4.1 | Rarely in small crystals; like
chrysolite |
|
| TETRADYMITE | Bi2 (TeS)3 | Variable | Pale steel gray | Metallic | 1.8 | 7.4 | Soils paper; found in gold-quartz
and igneous rocks |
|
| TETRAHEDRITE | 4Cu2S.Sb2S3 | Cu-52.1%
Sb-24.8% |
Gray to black | Metallic | Black | 3.0-4.5 | 4.4-5.1 | Wide spread and varied occurrences |
| TITANITE | CaTiSiO5 | TiO2-40.8% | Brown, gray,
yellow, green |
Adamantine | White | 5.0-5.5 | 3.4-3.6 | Usually confined to igneous
rocks; accessory rock |
| Topaz | (AlF)2SiO4 | No metal source | Many | Vitreous | 8.0 | 3.4-3.6 | Occurs in highly acid igneous
rocks |
|
| TOURMALINE | [(NaLiK)6(MgFe
Ca)3(AlCrFe)2B2SiO5] |
No metal source | Black, brown,&
many others. |
Vitreous to
Resinous |
White | 7.0-7.5 | 3.0-3.2 | Commonly found In granite,
gneiss and pegmatite veins |
| TREMOLITE | CaMg3(SiO3) 4 | No metal source | White to
dark gray |
Silky | 5.0-6.0 | 2.9-3.4 | Alters into actinolite | |
| TRIPHYLITE | LiFePO4 | Li-4.4% | Greenish gray,
bluish gray |
Vitreous,
Resinous |
4.8 | 3.5 | A phosphate of iron, manganese
and lithium |
|
| ULLMANNITE | NiSbS | Ni-27.6%
Sb-57.3% |
Steel gray
to white |
Metallic | Grayish | 5.3 | 6.4 | With galena and chalcopyrite |
| URANINITE | UO3,UO2
Variable |
Radium Source | Gray, green,
brown |
Submetallic
to Greasy |
Black, Gray,
Green |
5.5 | 9.0-9.7 | Of primary and secondary origin;
no definite formula |
| UVAROVITE | Ca3Cr2(SiO4)3 | No metal source | Green | Vitreous | 6.5-7.5 | 3.5 | A form of garnet | |
| VALENTINITE | Sb2O3 | Sb-83.5% | White | 2.5-3.0 | 5.6 | Occurs as oxidation product of
antimony |
||
| VANADINITE | (PbCl)Pb4(VO4)3 | Variable | Red, brown,
yellow |
Resinous | White or
Yellow |
2.7-3.0 | 6.6-7.1 | Uncommon; found in altered
lead deposits |
| VERMICULITE | 3MgO.(FeAl)2O3
3SiO2 |
Variable | Grayish | Talc-like | Uncolored | 1.5 | 2.7 | Becomes worm-like threads upon
heating-exfoliates |
| WILLEMITE | Zn2SiO4 | Zn-58.5% | Green, yellow,
brown |
Vitreous, Dull | White or
Grayish |
5.5 | 3.9-4.2 | Massive to granular; valuable
zinc ore |
| WITHERITE | BaCO3 | BaO-77.7% | Yellow ,brown | Vitreous
Pearly |
White | 3.4 | 4.4 | Often fibrous; usually with galena |
| WOLFRAMITE | (FeMn)WO4 | W-51.3% | Gray, brown, black | Submetallic | Reddish-
Brown |
5.0-5.5 | 7.2-7.5 | Differs from huebnerite in streak |
| WULFENITE | PbMoO4 | Pb-56.4%
Mo-26.2% |
Yellow, grayish | Resinous,
Adamantine |
White | 3.0 | 6.8 | Square, tubular crystals; often
with beveled edges |
| ZARATITE | NiCO3,2Ni(OH)2.
4H2O |
Ni-46.8% | Green | 3 | 2.6 | Emerald nickel; amorphous | ||
| ZINCITE | ZnO | Zn-80.3% | Red, yellow | Sub-Adamantine | Orange
Yellow |
4.0-4.5 | 5.4-5.7 | Associated with other zinc ores |
| ZIRCON | ZrSiO4 | ZrO2-67.2% | Yellow, gray | Adamantine | Colorless | 7.5 | 4.2-4.7 | In crystalline rocks; sometimes
in iron ore beds |
| Name | Formula | Percent
Metal |
Color | Lustre | Streak | Hardness | Spec.
Grav. |
Characteristics—Occurrence |
| ACTINOLITE | Ca(MgFe)3(SiO3)4 | No metal source | Green | Vitreous | 5.0-6.0 | 3.0-3.2 | Usually long crystals, columnar
or fibrous |
|
| ALBITE | NaAlSi3Os | Al2O3-19.5% | White to blue | Vitreous | White | 6.0-6.6 | 2.6-2.7 | Occurs with gneiss, schists, pegmatite and limestone |
| ALMANDITE | Fe3Al2(SiO4)3 | No metal source | Red to black | 6.5-7.5 | 3.1-4.3 | Accessory rock mineral; variety
of garnet |
||
| ALTAITE | PbTe | 61.9% Pb | Tin white
Yellow tinge |
Metallic | Grayish
Black |
3.0 | 8.2 | Associated with pyrite, galena,
tetrahedrite |
| ALUNITE | K2(Al2OH)6. (SO4)4 | K-9.4%.
Al-19.6% |
Pink-red | Vitreous
Pearly |
White | 3.8 | 2.7 | Associated with kaolin and pyrite |
| AMOSITE | (FeCaH2Mn)OSiO2 | No metal source | Gray to green | 2.2-2.3 | Long fibered asbestos | |||
| ANALCITE | NaAlSi2O6. 2H2O | Al2O3-23.2% | White | Vitreous | White | 5.0-5.5 | 2.2-2.3 | Common Zeolite; yields water |
| ANDALUSITE | Al2SiO5 | Al2O3-63.2% | White
Red-green |
Vitreous | 7.5 | 3.2 | Nearly square prisms; occurs with
gneiss, mica, schists |
|
| ANDRADITE | Ca3Fe2(SiO4)3 | No metal source | Green
Red-black |
Adamantine | 6.5-7.5 | 3.1-4.3 | Garnet and sometimes used as a
gem |
|
| ANGLESITE | PbSO4 | Pb-68.3% | Yellow
Green-gray |
Adamantine,
Vitreous |
White | 2.8-3.0 | 6.1-6.4 | Occurs in oxidation zones of lead
veins |
| ANORTHITE | CaAl2Si2O8 | Al2O3-36.7% | White, Gray-red | Vitreous | White | 6.0-6.5 | 2.7-2.8 | Occurs in igneous rocks |
| ANTHOPHYLLITE | (MgFe)SiO3 | No metal source | Gray
Brown-green |
Vitreous | Uncolored,
Grayish |
5.0 | 3.2-3.2 | Found in crystalline schists |
| APATITE | Ca4(CaF) (PO4)3 | P2O5-42.3% | Green-blue | Vitreous | White | 4.5-5.0 | 3.2 | Granular; frequently massive;
common in metamorphic rocks |
| ARAGONITE | CaCO3 | CaO-56% | White | Vitreous | White | 3.5-4.0 | 2.9 | Found in beds of iron ore and
gypsum |
| ARGENTITE | Ag2S | Ag-87.1% | Black | Metallic | Shiny Black | 2.0-2.5 | 7.2-7.4 | Cuts like lead; with silver, cobalt and nickel |
| ARGYRODITE | 3Ag2S.GeS2 | Ag-73.5% | Steel gray red tinge | Metallic | Grayish Black | 2.5 | 6.1 | Occurs with sphalerite, siderite and marcasite |
| ARSENOPYRITE | FeAsS | Fe-34.3%
As-46.0% |
Steel Gray | Metallic | Gray, Black | 5.5-6.0 | 5.9-6.3 | Widely spread; yields sparks and
garlic odor when struck |
| ATACAMITE | Cu2(OH)3Cl | Cu-59.5% | Green | Adamantine,
Vitreous |
Apple Green | 3.0-3.5 | 3.8 | Always of secondary origin with
copper ores |
| AZURITE | 2CuCo3.Cu(OH)2 | Cu-55.0% | Blue | Vitreous, Dull | Blue | 3.5-4.0 | 3.8-3.9 | Occurs with other copper minerals |
| BARITE | BaSO4 | BaO-65.7% | White, Blue-red | Vitreous | White | 2.5-3.5 | 4.3-4.6 | Found commonly as gangue of
lead-zinc ores |
| BAUXITE | Al2O3.3H2O | Al-34.9% | White-red
Brown-yellow |
Dull | Like Color | 1.0-3.0 | 2.6 | Chief ore of aluminum, occurs
massive |
| BENTONITE | (CaMg)O, SiO2 (AlFe)2O3 | No metal source | Blue | 1.0 | 2.1 | The clay of montmorillonite | ||
| BERYL | Be3Al2(SiO3)6 | Be—5%
Al2O3-19% |
White, Green-blue | Vitreous | White | 7.5-8.0 | 2.6-2.8 | Often imbedded in quartz; with
mica, feldspar |
| BERYLLONITE | NaBePO4 | Be-7.1% | White-yellow | Vitreous,
Brilliant |
5.8 | 2.8 | Found with beryl, feldspar, columbite | |
| BIOTITE | (HK)2(MgFe)2Al2(SiO4)3 | No metal source | Black-Brown | Pearly,
Vitreous |
White | 2.5-3.0 | 2.7-3.1 | Perfect cleavage into very thin
leaves |
| BISMITE | Bi2O3 | No metal source | Straw Yellow
White |
Pearly | 4.4 | Of secondary origin resulting
from oxidation |
||
| BISMUTH | Bi | Bi-100% | Silver White | Metallic | Silver White | 2.3 | 9.7 | Native; with cobalt, nickel; brassy
tarnish |
| BISMUTHINITE | Bi2S3 | Bi-81.2% | Lead gray | Metallic | Like Color | 2.0 | 6.4-6.5 | Occurs in form of thin coating |
| BISMUTITE | (BiO)2.CO3.H2O | No metal source | Green-white | 4.0 | 6.9-7.7 | Incrusting fibrous, or earthy and
pulverulent |
||
| BORAX | Na2B4O7.10 H2O | B2O3-36.6%
Na2O-16.2% |
White | Vitreous, Dull | White | 2.0-2.5 | 1.7 | Refer to introduction for characteristic taste |
| BORNITE | Cu3FeS4 | Cu-63.3% | Reddish | Metallic | Blackish Gray | 3.0-3.5 | 4.9-5.4 | Associated with chalcocite; massive |
| BOURNONITE | 3(PbCu2)S.Sb2S3 | Pb-24.7%
Cu-42.5% |
Steel gray
Iron black |
Metallic | Like Color | 2.5-3.0 | 5.7-5.9 | Occurs fine grained massive; brittle |
| BRAUNITE | 3Mn2O3.MnSiO3 | Mn-78.3% | Steel gray
Brownish black |
Submetallic | Like Color | 6.0-6.5 | 4.8 | Occurs in porphyry; brittle |
| BREITHAUPTITE | NiSb | Ni-32.5%
Sb-67.5% |
Copper red | Metallic | Reddish
Brown |
5.5 | 7.5 | Occurs with other sulfides and
silver minerals |
| BROCHANTITE | CuSO4.3Cu(OH)2 | Cu-56.2% | Green | Vitreous | Green | 3.5-4.0 | 3.9 | Found in oxidation zones of copper deposits |
| BRUCITE | MgO.H2O | MgO-69% | White to gray
blue, green |
Pearly,
Vitreous |
White | 2.5 | 2.4 | Associated with serpentine; secondary mineral |
| CALAMINE | AuTe2 | Au-43.6% | Bronze yellow
Silver-yellow tinge |
Yellowish
Gray |
2.5 | 9.0 | Similar to sylvanite, krennerite | |
| CALAVERITE | CaCO3 | CaO-56% | Many colors | Vitreous | White | 3.0 | 2.7 | Transparent to opaque; many
varieties |
| CALOMEL | HgCl | Hg-85%
Cl-15% |
White, yellow | Adamantine | Pale Yellow,
White |
1.0-2.0 | 6.5 | Associated with cinnabar |
| CARNALLITE | KMgCl3.6H2O | K-14.1%
Cl-38.3% |
White | Shining | 2.5 | 1.6 | Strongly phosphorescent; taste-bitter | |
| CARNOTITE | K2O.2U2O3.V2O3.3H2O Variable | Variable | Yellow | Vitreous, Dull | Yellow | 1.5 | Mixed with sands; yellow crystal
line powder |
|
| CASSITERITE | SnO2 | Sn-78.8% | Brown,black,
red |
Adamantine | White, Light
Brown |
6.0-7.0 | 6.8-7.1 | The source of tin; opaque to
translucent |
| CELESTITE | SrSO4 | Sr-47.7% | Light blue,
white, red |
Vitreous | White | 3.0-3.5 | 3.9-4.0 | Often associated with sulphur; in
beds of limestone |
| CERARGYRITE | AgCl | Ag-75.3% | Pearly gray | Waxy, greasy | White to
Gray |
1.0-1.5 | 5.6 | Cuts like wax; exposure changes
color to violet brown |
| CERUSSITE | PbCO3 | Pb-77.5% | White, gray | Adamantine | White | 3.0-3.5 | 6.5-6.6 | Specific gravity important; with
lead ores |
| CERVANTITE | 2Sb2O4 Sb2O3. Sb2O3 | Sb-79.4% | Yellow
reddish white |
Greasy, Pearly | White | 4.0-5.0 | 4.1-5.3 | Usually associated with stibnite |
| CHALCANTHITE | CuSO4.5H2O | CuO-31.8% | Blue | Vitreous | White | 2.5 | 2.1-2.3 | Formed by oxidation of copper
sulphides |
| CHALCEDONY | SiO2 | No metal source | Pale blue, gray
White to black |
Waxy | White | 7.0 | 2.6-2.7 | Often contains some disseminated
opal-silica |
| CHALCOCITE | Cu2S | Cu-79.8% | Black-Gray | Metallic | Like Color | 2.5-3.0 | 5.5-5.8 | Highly polished surface where cut |
| CHALCOMENITE | CuSeO3.2H2O | Cu-28.1%
Se-34.9% |
Blue | Vitreous | 2.5-3.0 | 3.8 | With various selenides of silver copper, and lead | |
| CHALCOPYRITE | CuFeS2 | Cu-34.6% | Brassy yellow | Metallic | Greenish
Black |
3.5-4.0 | 4.1-4.3 | Softer than pyrite; with pyrite,
galena, sphalerite |
| CHERT | SiO2 | No metal source | White-gray | 7.0 | 2.6 | Impure, coarse-grained, opaque
flint |
||
| CHLOANTHITE | NiAs2 Variable | NI-28.1%
As-71.9% |
Tin white,
steel gray |
Metallic | Grayish black | 5.8 | 6.5 | Associated with smaltite, cobalt,
silver and copper |
| CHROMITE | FeO.Cr2O3 | Cr-46.2% | Black | Vitreous | Dark Brown | 5.5 | 4.3-4.6 | Usually associated with serpentine; brittle |
| CHRYSOBERYL | BeOAl2O3 | BeO-19.8% | Green | Vitreous | White | 8.5 | 3.7-3.8 | Resembling green glass; brittle |
| CHRYSOCOLLA | CuOSiO2.2H2O | Cu-36.2% | Blue, green | Vitreous, Dull | White | 2.0-4.0 | 2.0-2.2 | Adheres to dry tongue; important ore of copper |
| CHRYSOLITE | (MgFe)2SiO4 | No metal source | Green | Vitreous | White or
Yellowish |
6.5-7.0 | 3.3 | Occurs in granular masses; brittle |
| CHRYSOTILE | H4Mg3Si2O9 | White, greenish | Metallic | White | 1.7 | 2.2 | Fibered asbestos; parallel fibers | |
| CINNABAR | HgS | Hg-86.2% | Red | Adamantine,
Submetallic |
Scarlet | 2.0-2.5 | 8.0-8.2 | Only important ore of mercury;
tastes “chalky” |
| CLAUSTHALITE | PbSe | Pb-72.4% | Lead gray | Metallic | Lead gray | 2.8 | 8.0 | Resembles granular galena |
| COBALTITE | CoAsS | Co-35.5% | Tin white,
steel gray |
Metallic | Grayish Black | 5.5 | 6.0-6.3 | Occurs commonly granular; ore
of cobalt |
| COLEMANITE | Ca2B6O11.5H2O | No metal source | White,
yellowish |
Brilliant,
Vitreous |
White | 4.0-4.5 | 2.4 | Usually occurs as geodes; brittle |
| COLUMBITE | (FeMn)(CbTa)2O6 | Variable-Ta2O5
3.3 to 31.5% |
Iron black | Submetallic | Dark Red,
Black. |
6.0 | 6.3 | Brittle; nearly pure niobate |
| COPPER | Cu | Cu-100% | Copper red | Metallic | Copper red | 2.8 | 8.8 | Tarnishes easily; malleable |
| CORUNDUM | Al2O3 | AI-52.9% | All colors | Vitreous,
Adamantine |
White | 9.0 | 3.9-4.1 | Brittle; very tough when compact |
| COSALITE | Pb2Bi2S6 | Pb-41.8%
Bi-42.1% |
Lead gray | Metallic | Black | 2.8 | 6.5 | In quartz veins; with pyrite,
sphalerite |
| COVELLITE | CuS | Cu-66.5% | Blue | Submetallic | Black | 1.5-2.0 | 4.6 | Opaque, turns blue when moistened |
| CROCIDOLITE | NaFe(SiO3)2.FeSiO3 | No metal source | Blue to green | Silky, Dull | Like Color | 4.0-5.0 | 3.2-3.3 | Fibrous masses; like asbestos,
valuable |
| CROCOITE | PbCrO4 | Pb-64.1%
Cr-16.1% |
Red | Adamantine | Orange
Yellow |
2.5 | 6.0 | Found with quartz, galena, vanadinite |
| CRYOLITE | Na3AlF6 | Al-13%
F-54.4% |
Snow white | Greasy to
Vitreous |
White | 2.5 | 3.0 | Appearance, hardness are distinctive |
| CUPRITE | Cu2O | Cu-88.8% | Red | Adamantine
to dull |
Red | 3.5-4.0 | 5.9-6.2 | Brittle; transparent to opaque;
fine grained |
| CYANITE | Al2SiO5 | Al-33.3% | White, to blue
or green |
Vitreous,
Pearly |
5.0-7.0 | 3.6 | Long, bladed triclinic crystals;
sometimes fibrous |
|
| DESCLOIZITE | 4RO.V2O5.H2O | Variable. V2O5 | Red, brown, black | Greasy | Orange | 3.5 | 6.0 | Associated with vanadinite |
| DIAMOND | C | C-100% | White, gray | Adamantine,
Greasy |
Ash Gray | 10.0 | 3.5 | Found with serpentine, placers,
magnetite, gold |
| DIASPORE | Al2O3. H2O | Al2O3-85% | Many colors | Vitreous | White | 6.5-7.0 | 3.4 | Occurs in thin scales; very brittle |
| DIATOMACEOUS
EARTH |
SiO2.n H2O | Yellow to brown | Vitreous | White to
Gray |
2.0 | 2.2 | Siliceous; scratches glass; light
In weight |
|
| DOLOMITE | CaMg (CO3)2 | CaO-30.4%
MgO-21.9% |
White, gray,
pink, yellow |
Vitreous,
Pearly |
White | 3.5-4.0 | 2.8-2.9 | Effervesces vigorously with hydrochloric acid |
| ENARGITE | 3CU2S. AS2S5 | Cu-48.4% | Iron black | Metallic | Black | 3.0 | 4.4 | Color and streak both black;
prismatic cleavage |
| EPIDOTE | Ca2(Al0H)(AlFe)2
(SiO4)3 |
No metal source | Green | Vitreous, Dull | White | 6.0-7.0 | 3.2-3.5 | Brittle; usually granular |
| EPSOM SALT | MgSO4.7 H2O | Mg-9.9% | White | Vitreous | White | 2.3 | 1.7 | Tastes bitter and saline; in mineral waters |
| ERYTHRITE | CO3AS2O8.8H2O | Co-29.5% | Crimson, gray | Pearly | Paler than
Color |
1.5-2.5 | 3.0 | Deposits of secondary origin;
with cobalt ores |
| FERBERITE | FeWO4 | W-60.6% | Brown, black | Metallic | 5.0-5.5 | 7.2-7.5 | Found with other tungsten ores | |
| FLUORITE | CaF2 | F-48.9% | All colors | Vitreous | White | 4.0 | 3.0-3.3 | Octahedral cleavage; brittle |
| FRANKEINITE | (ZnFeMn)O
(FeMn)2O3 |
Zn-14.2%
Mn-35.7% |
Iron black | Metallic | Brown to
Black |
5.5-6.5 | 5.2 | Usually associated with zincite;
sometimes magnetic |
| GALENA | PbS | Pb-86.6% | Lead gray | Metallic | Lead Gray | 3.0 | 7.4-7.6 | Very brittle; cubic cleavage |
| GARNET | Various | No metal source | Red, brown,
yellow |
Vitreous | White | 6.5-7.5 | 3.2-4.3 | Usually imbedded in mica or
other schists |
| GARNIERITE | H2(NiMg)SiO4 | Ni-25% to 30% | Green | Dull, greasy | Greenish.
White |
2.0-4.0 | 2.4 | Amorphous; source of nickel;
with serpentine, chromite |
| GENTHITE | 2NiO,2MgO.
3SiO2.6 H2O |
Ni-22.6% | Green | Dull, greasy | Greenish.
White |
2.0-4.0 | 2.4 | Similar to garnierite |
| GIBBSITE | Al(0H)3 | Al-34.6% | White, green | Pearly | 2.0-3.5 | 2.4 | Occurs under same conditions as
bauxite |
|
| GOLD | Au | Au-100% | Golden | Metallic | Golden
Yellow |
2.8 | 15.6-19.3 | Malleable; does not famish;
many associations |
| GRAPHITE | C | C-100% | Black | Dull,
Submetallic |
Dark Gray,
Iron Black |
1.0-2.0 | 2.2 | Soft; marks paper; feels greasy;
often impure |
| GREENOCKITE | CdS | Cd-77.7% | Yellow | Adamantine | Yellow to red | 3.0-3.5 | 5.0 | Usually occurs as coating on zinc
minerals |
| GROSSULARITE | Ca3Al2(SiO4)3 | No metal source | White, green,
yellow |
Vitreous | White | 6.5-7.5 | 3.4-3.7 | Often imbedded in mica and
schists; limestones |
| GYPSUM | CaSO4.2H2O | CaO-32.6% | White, red | Vitreous | White to
Gray |
1.5-2.0 | 2.3 | In limestones, shales; monoclinic
crystals |
| HALITE | NaCl | Na-39.4% | White | Vitreous | White | 2.5 | 2.1-2.6 | Taste-saline. Important source of
sodium |
| HALLOYSITE | H4Al2O3.2SiO2.H2O | No metal source | White, green,
blue, red |
Pearly, Waxy,
dull |
1.0-2.0 | 2.0-2.2 | Often occurs in veins of ore as
secondary product |
|
| HAUSMANNITE | Mn3O4 | Mn-72% | Black,brown | Metallic | Brown | 5.3 | 4.7 | Associated with other manganese
minerals |
| HEMATITE | Fe2O3 | Fe-70% | Brown, red, black | Metallic, Dull
Submetallic |
Red, Brown | 5.5-6.5 | 4.9-5.3 | Becomes magnetic upon heating
under reducing conditions |
| HESSITE | Ag2Te | Ag-63% | Gray | Metallic | Black | 2.5-3.0 | 8.3-8.9 | With chalcopyrite, pyrite, and
sphalerite |
| HORNEBLENDE | Variable | Variable | White, green,
black |
Vitreous | 5.0-6.0 | 3.2 | Many varieties; one of the amphiboles | |
| HUEBNERITE | MnWO4 | Mn-18.1%
W-60.7% |
Brown | Submetallic | Yellowish
Brown |
5.0-5.5 | 7.2-7.5 | Occurs with other tungsten minerals and galena |
| HYDROZINCITE | ZnCo3.2Zn(OH)2 | Zn-59.5% | White, gray,
yellow |
Dull | White | 2.0-2.5 | 3.6-3.8 | Usually associated with other
zinc ores |
| HYPERSTHENE | (FeMg)SiO3 | No metal source | Black | Pearly | Gray | 5.0-6.0 | 3.5 | Occurs in foliated or platy masses |
| ILMENITE | FeTiO3 | Ti-31.6% | Iron black | Metallic,
Submetallic |
Brown | 5.0-6.0 | 4.5-5.0 | Magnetic; with pyrite, horneblende,
feldspars |
| IODYRITE | Agl | Ag-46% | Yellow, green | 3.0-4.0 | 5.6-5.7 | Usually in thin plates; rare | ||
| IRIDIUM | Variable | Variable | White | Metallic | 6.7 | 22.7 | With platinum and allied metals | |
| IRIDOSMENE | IrOs(RhPtRu | Alloy-100% | Tin White | Metallic | 6.0-7.0 | 19.3-21.1 | Rare metals alloy | |
| JAMESONITE | 2PbS.Sb2S3 | Pb-50.8%
Sb-29.5% |
Gray | Metallic | Grayish
Black |
2.0-3.0 | 5.5-6.0 | Usually associated with quartz;
brittle |
| JEFFERISITE | Variable | Variable. | Yellowish brown | Pearly | White | 1.5 | 2.3 | Mica loosely combined with water; with serpentine |
| KAINITE | MgSO4.KCl.3H2O | KCl-30.0% | White to red | Vitreous | 2.8 | 2.1 | Found in granular masses; with
halite, sylvite |
|
| KAOLINITE | H4Al2Si2O9 | Al2O3-39.5% | White, yellow | Pearly | Same as Color | 2.0-2.5 | 2.6 | Widespread; earthy odor; clay |
| KERMESITE | Sb2S2O | Sb-75.3% | Cherry | Adamantine,
Metallic |
Brownish
Red |
1.3 | 4.6 | Occurs with stibnite |
| KIESERITE | MgSO4.H2O | Mg-17.6% | White, yellow | Vitreous | 3.3 | 2.6 | Often with gypsum and carnallite | |
| LEPIDOLITE | KLi[Al(OHF) 2]
Al(SiO3)3 |
Small amount
of Li |
Red, lilac, white | Pearly | White | 3.0 | 2.8-3.3 | Occurs in granite, gneiss; with
muscovite |
| LEUCITE | KAI(SiO3)2 | K2O-21.5%
Al2O3-23.5% |
Gray | Vitreous, Dull | White | 5.5-6.0 | 2.5 | Occurs only in igneous rocks,
particularly recent lava flows |
| LIMESTONES | Chiefly CaCO3 | Ca-40% | Variable | Dull | White | 3.0 | 2.7 | Widely distributed; large deposits |
| LIMONITE | 2Fe2O3-3H2O | Fe-59.9% | Brown, yellow | Submetallic | Yellowish
Brown |
5.0-5.5 | 3.6-4.0 | Massive, fibrous or porous; magnetic after fusing |
| LINNAEITE | CO3S4 | Co-58.0% | Steel gray | Metallic | Blackish
Gray |
5.5 | 4.8-5.0 | Copper red tarnish; in gneiss
with chalcopyrite |
| LIYINGSTONITE | HgS.2Sb2S3 | Hg-22.0% | Lead gray | Metallic | Red | 2 | 4.81 | Resembles stibnite; fuses easily |
| MAGNESITE | MgCO3 | Mg-28.9% | White to black | Vitreous | White | 4.0-4.5 | 3.1 | Often associated with serpentine;
chalk-like |
| MAGNETITE | FeO.Fe2O3 | Fe-72.4% | Iron black | Metallic,
Submetallic |
Black | 5.5-6.5 | 5.2 | Strongly magnetic; many associations |
| MALACHITE | CuCO3.Cu(OH)2 | Cu-57.5% | Green | Silky | Green | 3.5-4.0 | 4.0 | Usually associated with other
copper minerals |
| MANGANITE | Mn2O3.H2O | Mn-62.5% | Iron black,
steel gray |
Metallic,
Submetallic |
Brown | 4.0 | 4.2-4.4 | Hardness and streak are distinctive |
| MARBLE | Chiefly CaCO3 | Ca-40% | Variable | Vitreous,
Earthy |
White, Gray | 3.0 | 2.7 | Varieties based on accidental Impurities |
| MARCASITE | FeS2 | Fe-46.6% | Yellow | Metallic | Grayish,
Brown, black |
6.0-6.5 | 4.9 | Same uses as pyrite; brittle |
| MARMATITE | (ZnFe)S Variable | Zn-46.5%
to 56.9% |
Yellow, brown,
black |
Adamantine | Brownish | 5.0 | 3.9-4.2 | Closely allied with galena; common zinc ore |
| MEUCONITE | CuO | Cu-79.9% | Black | Earthy,
Metallic. |
3.0-4.0 | 6.5 | Sublimation product in volcanic
regions |
|
| MELILITE | Ca12Al4Si9O36 | White, yellow,
green, brown |
Vitreous | 5 | 2.9-3.1 | Formed from magmas; common
in Portland cement |
||
| MERCURY | Hg | Hg-100% | Tin white | Metallic | 13.59 | Liquid; rarely found in metallic
state |
||
| METACINNABARITE | HgS | Hg-86.2% | Grayish black | Metallic | Black | 3 | 7.7 | Found in upper portions of mercury deposits |
| MILLERITE | NiS | Ni-64.8% | Yellow | Metallic | Greenish
Black |
3.0-3.5 | 5.3-5.7 | Valuable ore of nickel; needle
like crystals |
| MIMETITE | (PbCl)Pb4AS3O12 | Pb-69.7% | Yellow to brown | Resinous | White | 3.5 | 7.0-7.3 | A minor ore of lead; uncommon
species |
| MOLYBDENITE | MoS2 | Mo-60% | Lead gray | Metallic | Greenish Gray | 1.0-1.5 | 4.7-4.8 | Greasy; makes dark greenish
mark on glazed paper |
| MOLYBDITE | MoO3 | Mo-66.67% | Yellow | Adamantine,
Pearly |
1.5 | 4.5 | Occurs with molybdenite | |
| MONAZITE | (CeLaDy)PO4.ThSiO4 | ThO2-9% | Yellow, brown | Resinous | White | 5.0-5.5 | 4.9-5.3 | Rounded grains; with gold,
chromite, iron |
| MOTTRAMITE | Variable | Variable | Black, yellow | Resinous | Yellow | 3 | 5.8 | A vanadate of lead and copper |
| MUSCOVITE | H2KAl3(SiO4)2 | Variable | Yellowish white | Vitreous,
Pearly |
White | 2.0-2.5 | 2.8-3.0 | Perfect cleavage into very thin
leaves |
| NAUMANNITE | (Ag2Pb)Se | Ag-43.0% | Iron black | Metallic | Iron Black | 2.5 | 8 | Malleable; in cubic crystals; selenide
of silver and lead |
| NEPHELITE | NaAlSiO4 | No metal source | White, yellow | Vitreous,
Greasy |
White | 5.5-6.0 | 2.5-2.7 | Widely distributed in igneous
rocks; usually massive |
| NICCOLITE | NiAs | Ni-44.1%
As-55.9% |
Copper red | Metallic | Brownish
Black |
5.0-5.5 | 7.3-7.7 | Often found with a green coating; brittle; compact |
| NITRE | KNO3 | K-38.6%
N-13.9% |
White | Vitreous | White | 2 | 2.1 | Tastes saline and cooling; salt
petre |
| OLIVINE | (MgFe)2.SiO4 | No metal source | Green | Vitreous | White or
Yellowish |
6.5-7.0 | 3.3 | Occurs in granular masses; brittle |
| OPAL | SiO2.nH2O | No metal source | All colors | Greasy,
Vitreous |
White | 5.5-6.5 | 1.9-2.3 | Amorphous silica; very smooth |
| ORPIMENT | AS2S3 | As-61% | Lemon yellow | Resinous | Lemon
Yellow |
1.5-2.0 | 3.5 | Usually associated with realgar;
seldom valuable |
| ORTHOCLASE | KAlSi3O8 | Al2O3-18.4% | Red, gray,
yellow, white |
Vitreous, Dull | White | 6.0-6.5 | 2.5-2.6 | Common constituent of igneous
rocks; most common of all silicates |
| PENTLANDITE | (FeNi)S | Fe-42.0%
Ni-22.0% |
Yellow-bronze | Metallic | Black | 3.5-4.0 | 4.6-5.0 | Associated with pyrrhotite, millerite,
chalcopyrite, etc. |
| PETZITE | (AuAg)2 Te | Au-25.5%
Ag-42% |
Gray to black | Metallic | Gray | 2.5 | 9.1 | A rare but valuable ore of gold
and silver; often tarnishes |
| PHOSPHATE ROCK | Ca3(PO4)2 | P2O5-32.1% | Gray | Dull | Gray | 5 | 3.2 | Occurs in massive deposits |
| PLATINUM | Pt | Pt-100% | Tin white,
steel white |
Metallic | Shiny Gray | 4.5 | 17.0 | Sometimes magnetic; with gold
and chromite |
| POLIANITE | MnO2 | Mn-63.2% | Steel gray,
iron gray |
Metallic | Black | 6.3 | 4.9 | Looks like pyrolusite, but harder
and dryer; rare |
| POLYBASITE | 9Ag2S.Sb2S3 | Ag-75.6%
Sb-9.4% |
Iron black | Metallic | Black | 2.0-3.0 | 6.0-6.2 | With chalcopyrite, calcite, pyrargyrite, stephanite |
| POWELLITE | Ca(Mo,W)O4 | Variable | Greenish yellow | Resinous | 3.5 | 4.5 | Often associated with scheelite | |
| PROUSTITE | 3Ag2S.As2S3 | Ag-65.5% | Scarlet | Adamantine,
Dull |
Scarlet | 2.0-2.5 | 5.6 | Usually associated with other silver ores |
| PSILOMELANE | MnO2.H2O.K2.BaO2 | Black | Submetallic
Dull |
Black,
Brownish Black |
5.0-6.0 | 3.7-4.7 | Hardness and appearance distinctive; with pyrolusite | |
| PYRARGYRITE | 3Ag2S.Sb2S3 | Ag-60%
Sb-22.2% |
Black, reddish | Adamantine,
Metallic |
Purplish Red | 2.5 | 5.8-5.9 | Often associated with argentite
and proustite |
| PYRITE | FeS2 | Fe-46.7% | Brass yellow | Metallic | Greenish
Brn.-Blk. |
6.0-6.5 | 5.0 | In all types of rock; used in
manufacture of H2SO4 |
| PYROLUSITE | MnO2 | Mn-63.2% | Black, dark gray | Metallic, Dull | Black,
Blu.-Blk |
1.0-2.5 | 4.8 | Soils fingers; hardness and streak
are distinctive |
| PYROMORPHITE | Pb3Cl(PO4)3 | Pb-76.4% | Yellow | Greasy,
Adamantine |
White,
Yel.-White |
3.5-4.0 | 5.9-7.1 | Alteration product of lead minerals |
| PYROPE | Mg3Al2(SiO4) 3 | No metal source | Red | Vitreous,
Resinous |
6.5-7.6 | 3.7 | If transparent, then prized as a
gem. Precious garnet. |
|
| PYROPHYLLITE | HAI(SiO3)2 | Al2O3-28.3% | White, brown | Pearly, Dull | White | 1.0-2.0 | 2.8-2.9 | Feels greasy or soapy |
| PYROXENE | Ca(AlMgMnFe)
(SiO3)2 |
No metal source | Green | Vitreous, Dull | White to
Green |
5.0-6.0 | 3.3 | Commonly in igneous rocks;
particularly volcanic |
| PYRRHOTITE | Fe5S6 to Fe16S17 | Fe-61.5%
Variable |
Brownish yellow | Metallic | Grayish Black | 3.5-4.6 | 4.6 | Only magnetic sulphide and
therefore distinctive |
| QUARTZ | SiO2 | Si-46.9% | Colorless,
all colors |
Vitreous | White | 7.0 | 2.65-2.66 | Different colors and varieties due
to impurities |
| REALGAR | AsS | As-70.1% | Orange | Resinous | Orange | 1.5-2.0 | 2.6 | Usually associated with Orpiment;
flexible |
| RHODOCHROSITE | MnCo3 | MnO-61.7% | Usually red | Vitreous,
Pearly |
White | 3.5-4.5 | 3.5-3.6 | Becomes darker upon exposure;
an ore of manganese |
| RHODONITE | MnSiO3 | Mn-42.0% | Brownish red | Vitreous, Dull | White | 5.5-6.5 | 3.4-3.7 | With calcite, Zincite, tetrahedrite |
| ROSCOELITE | H8K(MgFe)(AIV)4
(SiO3)12 |
Variable | Brown | Pearly | Soft | 2.9 | Vanadium mica in which vanadium replaced aluminum | |
| RUBY | Al2O3 | Al-52.9% | Many colors | Adamantine,
Vitreous |
9.0 | 4.0 | Brittle; when compact very
tough; variety of corundum |
|
| RUTILE | TiO2 | Ti-60% | Brown, red,
black |
Adamantine,
Submetallic |
Light
Brown |
6.0-6.5 | 4.2 | Frequently associated with iron |
| SCHEELITE | CaWO4 | W-63.9% | White-Yellowish | Vitreous,
Adamantine |
White | 4.5-5.0 | 5.9-6.1 | Brittle; important ore of tungsten |
| SENARMONTITE | Sb2O3 | Sb-83.6% | Colorless, grayish | Vitreous, Dull | 2 | 5.3 | Formed by oxidation of stibnite | |
| SERPENTINE | H4Mg3Si2O2 | Mg-43% | Green, blackish
or yellow, white |
Wax-like,
Silky |
White | 4.0 | 2.5-2.6 | Feels smooth and sometimes
slightly greasy |
| SIDERITE | FeCO3 | Fe-48.3% | Brown, gray | Vitreous,
Pearly, Dull |
White to
Yellow |
3.5-4.0 | 3.9 | Magnetic upon heating; an ore
of iron |
| SILVER | Ag | Ag-100% | Silver white | Metallic | Silver-
White |
2.8 | 10.5 | Tarnishes easily; with gold, copper. etc. |
| SMALTITE | CoAS2 | Co-28.2%.
As-71.8% |
Tin white,
steel gray |
Metallic | Grayish Black | 5.5-6.0 | 5.7-6.8 | Occurs usually in veins with cobalt-nickel ores |
| SMITHSONITE | ZnO.CO2 | Zn-52% | Green, gray, blue | Vitreous, Dull | White, grayish | 5.0 | 4.3-4.5 | With sphalerite and calamine |
| SODA NITRE | NaNO3 | White, reddish
brown; colorless |
Vitreous | White | 1.8 | 2.3 | Taste-cooling; incrustations in
beds; massive |
|
| SPERRYLITE | PtAS2 | Pt-56.6%
As-43.4% |
Tin white | Metallic,
Brilliant |
Black | 6.5 | 10.6 | Found with gold-quartz, covellite,
limonite |
| SPESSARTITE | Mn3Al2(SiO4) 3 | No metal source | Purplish, red | Vitreous | 3.5-4.0 | 3.9-4.1 | Often associated with galena,
chalcopyrite |
|
| SPHALERITE | ZnS | Zn-67.1% | Brown, yellow,
reddish |
Submetallic,
Resinous |
Light Brown,
Yellow |
8.0 | 3.5-4.1 | Occurs in igneous rocks; often
contact mineral |
| SPINEL | MgOAl2O3 | Al2O3-71.8%
MgO-28.2% |
Yellowish,
gray, brown. |
Vitreous, Dull | White to
Gray |
6.5-7.0 | 3.1-3.2 | Occurs in granite rocks; with lepidolite |
| SPODUMENE | LiAl(SiO3)2 | Al2O3-27.4%
Li2O-8.4% |
White, grayish | Vitreous, Dull | White | 4.0 | 4.5 | Has appearance of bronze |
| STANNITE | Cu2S.FeS.SnS2 | Sn-27.5%
Cu-29.5% |
Steel gray,
iron black |
Metallic | Blackish | 2.0-2.5 | 6.2-6.3 | Associated with other silver ores |
| STEPHANITE | 5Ag2S.Sb2S3 | Ag-68.5% | Iron black | Metallic | Iron Black | 2.0-2.5 | 6.2-6.3 | Associated with other silver ores |
| STIBNITE | Sb2S3 | Sb-71.8% | Lead gray | Metallic | Lead Gray,
Black |
2.0 | 4.5-4.6 | Tarnishes black; with gold-quartz,
galena |
| STRONTIANITE | SrCO3 | Sr-59.3% | Yellow to brown
Green |
Vitreous,
Greasy |
White to.
Gray |
3.5-4.0 | 3.7 | Like aragonite in structure; in
dependent beds |
| SULFUR | S | S-100% | Yellow | Greasy,
Adamantine |
Pale Yellow | 2.0 | 2.0 | With celestite, clay, aragonite,
gypsum |
| SYLVANITE | (AuAg)Te2 | Au-24.5%
Ag-13.4% |
White to steel gray | Metallic | Same as
Color |
1.5-2.0 | 7.9-8.3 | Telluride of gold and silver |
| SYLVITE | KCl | K-52.4% | White,
yellowish red |
Vitreous | White | 2.0 | 1.98 | Taste-saline; soluble; bitter |
| TALC | H2Mg3(SiO3)4 | Mg-19.2%
Si-29.6% |
Green to white | Pearly | White | 1.0-1.5 | 2.7-2.8 | Common; feels greasy; extensive
beds |
| TANTALITE | FeTa2O6 | Variable
Ta2O6-65.6% |
Iron black | Submetallic,
Greasy, Dull |
Reddish
Brown |
6.3 | 5.3-7.3 | Iron and manganese content variable; with columbite |
| TENNANTITE | Cu8As2S7
Variable |
Cu-57.5%
Variable |
Steel gray,
iron black |
Metallic | Black, Reddish Brown | 3.0-4.5 | 4.4-4.5 | With chalcopyrite, sphalerite,
galena, tetrahedrite |
| TENORITE | CuO | Cu-79.9% | Black | Metallic | 3.0 | 5.8-6.3 | Sublimation product in volcanic
regions |
|
| TEPHROITE | Mn2SiO4 | No metal source | Red, ash gray | Vitreous | 6.5-7.0 | 4.0-4.1 | Rarely in small crystals; like
chrysolite |
|
| TETRADYMITE | Bi2 (TeS)3 | Variable | Pale steel gray | Metallic | 1.8 | 7.4 | Soils paper; found in gold-quartz
and igneous rocks |
|
| TETRAHEDRITE | 4Cu2S.Sb2S3 | Cu-52.1%
Sb-24.8% |
Gray to black | Metallic | Black | 3.0-4.5 | 4.4-5.1 | Wide spread and varied occurrences |
| TITANITE | CaTiSiO5 | TiO2-40.8% | Brown, gray,
yellow, green |
Adamantine | White | 5.0-5.5 | 3.4-3.6 | Usually confined to igneous
rocks; accessory rock |
| Topaz | (AlF)2SiO4 | No metal source | Many | Vitreous | 8.0 | 3.4-3.6 | Occurs in highly acid igneous
rocks |
|
| TOURMALINE | [(NaLiK)6(MgFe
Ca)3(AlCrFe)2B2SiO5] |
No metal source | Black, brown,&
many others. |
Vitreous to
Resinous |
White | 7.0-7.5 | 3.0-3.2 | Commonly found In granite,
gneiss and pegmatite veins |
| TREMOLITE | CaMg3(SiO3) 4 | No metal source | White to
dark gray |
Silky | 5.0-6.0 | 2.9-3.4 | Alters into actinolite | |
| TRIPHYLITE | LiFePO4 | Li-4.4% | Greenish gray,
bluish gray |
Vitreous,
Resinous |
4.8 | 3.5 | A phosphate of iron, manganese
and lithium |
|
| ULLMANNITE | NiSbS | Ni-27.6%
Sb-57.3% |
Steel gray
to white |
Metallic | Grayish | 5.3 | 6.4 | With galena and chalcopyrite |
| URANINITE | UO3,UO2
Variable |
Radium Source | Gray, green,
brown |
Submetallic
to Greasy |
Black, Gray,
Green |
5.5 | 9.0-9.7 | Of primary and secondary origin;
no definite formula |
| UVAROVITE | Ca3Cr2(SiO4)3 | No metal source | Green | Vitreous | 6.5-7.5 | 3.5 | A form of garnet | |
| VALENTINITE | Sb2O3 | Sb-83.5% | White | 2.5-3.0 | 5.6 | Occurs as oxidation product of
antimony |
||
| VANADINITE | (PbCl)Pb4(VO4)3 | Variable | Red, brown,
yellow |
Resinous | White or
Yellow |
2.7-3.0 | 6.6-7.1 | Uncommon; found in altered
lead deposits |
| VERMICULITE | 3MgO.(FeAl)2O3
3SiO2 |
Variable | Grayish | Talc-like | Uncolored | 1.5 | 2.7 | Becomes worm-like threads upon
heating-exfoliates |
| WILLEMITE | Zn2SiO4 | Zn-58.5% | Green, yellow,
brown |
Vitreous, Dull | White or
Grayish |
5.5 | 3.9-4.2 | Massive to granular; valuable
zinc ore |
| WITHERITE | BaCO3 | BaO-77.7% | Yellow ,brown | Vitreous
Pearly |
White | 3.4 | 4.4 | Often fibrous; usually with galena |
| WOLFRAMITE | (FeMn)WO4 | W-51.3% | Gray, brown, black | Submetallic | Reddish-
Brown |
5.0-5.5 | 7.2-7.5 | Differs from huebnerite in streak |
| WULFENITE | PbMoO4 | Pb-56.4%
Mo-26.2% |
Yellow, grayish | Resinous,
Adamantine |
White | 3.0 | 6.8 | Square, tubular crystals; often
with beveled edges |
| ZARATITE | NiCO3,2Ni(OH)2.
4H2O |
Ni-46.8% | Green | 3 | 2.6 | Emerald nickel; amorphous | ||
| ZINCITE | ZnO | Zn-80.3% | Red, yellow | Sub-Adamantine | Orange
Yellow |
4.0-4.5 | 5.4-5.7 | Associated with other zinc ores |
| ZIRCON | ZrSiO4 | ZrO2-67.2% | Yellow, gray | Adamantine | Colorless | 7.5 | 4.2-4.7 | In crystalline rocks; sometimes
in iron ore beds |
Source: This article is a reproduction of an excerpt of “In the Public Domain” documents held in 911Metallurgy Corp’s private library.