Placer Mining Cost
In work on shallow placer deposits by individuals the results differ greatly, both according to the strength and skill of the worker and to the contents of the gravel. Under the best conditions of climate a strong, well-nourished, American digger may be able to raise by the shovel from 10 to 12 cubic yards of […]
Placer Gold Mining Methods
The gold deposits grouped together under the name of “ placers ” comprise sands, gravels, or any loosely coherent or non-coherent alluvial beds containing gold. They have accumulated owing to the action of running water, in the beds of rivers, or on the adjoining inundation plains, or on sea beaches. They fall naturally into two […]
Dissemination of Gold
Dissemination of Gold.—The wide distribution of gold in minute quantities throughout the world was pointed out by W. E. Dubois, an Assayer in the United States Mint, in 1861, and is further attested by a large number of specimens now in the Percy collection. These consist of small specks of gold of different sizes which […]
Gold Compounds
Gold is characterised chemically by an extreme indifference to the action of all bodies usually met with in nature. Its simpler compounds are formed with difficulty, and decompose readily, especially when heated. The result is that gold is found in nature chiefly in the metallic form, and the mineralogist has, therefore, few compounds to consider. […]
Gold Silicates
The existence of auro-silicates is now admitted without dispute, and gold has for centuries been used to impart colour to glasses, the method used being as follows: A solution of chloride of gold is added to a mixture of sand with alkalies and alkaline earths or lead, and the whole is then fused, and colourless […]
Gold Sulfite
Sulphites of Gold, alkaline sulphites, or sulphur dioxide, which reduce gold trichloride easily, do not produce the same effect on a solution of an alkaline aurate. If sodium bisulphite is added to a boiling solution of sodium aurate (NaAuO2) a yellowish precipitate is formed, soluble in excess of sodium bisulphite, and consisting of a double […]
Gold Oxides
Aurous Oxide, Au2O This gold oxide is prepared by decomposing aurous chloride, AuCl, or the corresponding bromide by potash in the cold (Berzelius) when a violet precipitate forms, which is blackish when moist, but greyish when dry. When freshly precipitated it is soluble both in alkalies and in cold water, forming an indigo blue solution, with […]
Gold Cyanide Formulas
Cyanogen and gold unite in two proportions, forming aurous and auric cyanides, but the latter is only known with certainty in combination. Aurous Cyanide, AuCy, is obtained by heating aurocyanide of potassium, KAuCy2, with hydrochloric or nitric acid and washing with water. It is a lemon-yellow crystalline powder, insoluble in water, and unaltered by exposure […]
Gold Bromides
Gold Protobromide, AuBr, is a yellowish-green powder obtained by heating the tribromide to about 140°. It is insoluble in water, but is decomposed by it, metalic gold and the tribromide being formed; the change is especially rapid on boiling, and is hastened by the presence of hydrobromic acid. Auro-auric Bromide, Au2Br4, is produced by the […]
Gold Chloride
Gold Monochloride or Aurous Gold Chloride “AuCl” is a salt is prepared by heating the trichloride to 185° in air for twelve hours. It is non-volatile and unaltered at ordinary temperatures and pressure by dry air, even when exposed to light, but begins to decompose at temperatures above 160°, and the decomposition is complete if it is […]