Ore Sampling Methods: Good & Proper
From the old-fashioned “ grab-sample ” to the modern timing- device, which takes a machine-sample with mathematical precision, there is a wide gap, which was only crossed by many years of toil and unremitting endeavor. Even to-day, notwithstanding the advancement in the art, “ grab-sampling ” is still practiced—sometimes to afford the unscrupulous mine-promoter a […]
Hyperfusible
Hyperfusible, adj. (of a substance) capable of reducing the melting ranges in end-stage magmatic fluids. The course of fractional crystallization of subalkaline magmas epitomized in the schematic reaction series is the net result of all the factors that contribute to phase equilibrium in the poly-component system concerned. Just what the components of the system may […]
Chemistry of Natural Borates
Since the borates which supply commerce with most of the raw materials for conversion into borax as it is used in the arts now come from old lake-beds or inland-sea deposits, their chemical relations and development are quite like those of saline deposits generally. While a general sequence of salts in the precipitations from complex […]
Borax Ore Deposits & Geology
A complete transformation has taken place in the borax industry. A most remarkable factor in this radical change in method of producing the crude borates has been its removal from the realm of industrial chemistry to the field of mining. With the development of extensive deposits of borate-minerals interstratified in thick sequences of Tertiary clays and […]
Volatility of Metallic Chlorides
In Table I are cited data on the vapor pressures of the common metallic chlorides. The temperatures given are in the region of magmatic temperatures, except where a high vapor pressure is developed at a much lower temperature. Because of the volatility of chlorides, and because direct observation of volcanic sublimates shows their presence, it […]
Economic Geology
Understanding the feed to processing operations is key to maximizing cash flow (economic value). Unfortunately the subject of economic geology is not covered within most undergraduate programs preparing students who enter the mining industry as process engineers. The good news is that there are reference materials available to help people learn these subjects. Some good […]
Underground Gold Mine Development Sampling & Ore Valuation
This paper is intended, in the light of recent investigations, to call attention to some of the essential features of good practice in sampling and mine-valuation. Mine sampling may be divided broadly into two classes: development-sampling and computation of ore-reserves; and, stope-sampling and estimation of stope-values. Development Sampling It is with development-sampling only that this […]
Adjustable Thermo-Electric Pyrometer
Frequently in using a thermo-electric pyrometer for measuring the temperature of a furnace, a hole is drilled at the back or side of the furnace, through which is introduced the tube containing the thermocouple. At times the couple is left almost where it drops, for the reason that it soon becomes too hot to be […]
Base Metal Deposits
Some epithermal veins, worked for gold in the upper, enriched zones, consist mainly of base-metal minerals below the enriched zone. The Smuggler vein at Telluride, Colorado, as shown by Lindgren, is an outstanding example. Its sulphides constitute 2 or 3 per cent of the vein and include principally pyrite, galena, zinc blende, and chalcopyrite accompanied […]
Gold Ore Deposits
The volcanic source of gold deposits is also most clearly indicated in the Cripple Creek district, Colorado, where the deposits of commercial grade are either within a complex volcanic neck or extend for only short distances into the surrounding rocks. It is true that similar mineralization has taken place for considerable distances from the neck, […]