The Elements of economic geology

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Monograph

Identifikator:: 1773832379

URN:: urn:nbn:de:zbw-retromon-172798

Document type:: Monograph

Author:: Gregory, John W. http://d-nb.info/gnd/11683014X

Title:: The Elements of economic geology

Place of publication:: London

Publisher:: Methuen

Year of publication:: 1928

Scope:: XIV, 312 S.; graph. Darst.

Digitisation:: 2021

Collection:: Economics Books

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Chapter

Document type:: Monograph

Structure type:: Chapter

Title:: Part II. Ore deposits

Collection:: Economics Books

78 ECONOMIC GEOLOGY from a wide outcrop would have been scattered and only the poorer marginal deposits left. VARIATIONS IN PricE oF Tin—For many years the normal price of tin ranged a little below £100 a ton; in 1916 it was £162 a ton, in 1920, £423 a ton, and after falling to £130 in 1922, rose in 1926 to over £300 a ton. The price has been subject to sudden fluctuations, and ore deposits that were FiG. 27.—RELATION OF THE Wipte OF GRANITE 10 Tin PLACERS. Relation of the width of granite outcrop to richness of tin placers. The surface at A would bear washings from the tip of the granite which is rich in cassiterite. In the surface at B, the poor lower margin of the granite is exposed and the alluvial tin ore will be less abundant. The cassiterite in the granite represented by black dots, paying well are for a time rendered worthless. Sensational statements made during a quarrel between two groups of Chicago meat packers led to a fall in the demand for canned meat, and therefore for tinned plate, that closed nearly all the tin mines in Tasmania. The tradespeople at the mines were ruined, owing to a commercial quarrel at their antipodes. TUNGSTEN (W; sp. gr, 19:1; at. wt, 184 ; melting-point, 3100° F.) The main use of tungsten is for high-speed tool steel, which remains hard and tough to an almost red heat. As the melting-point of tungsten is high and its rate of expansion nearly the same as that of glass and platinum, it is used for electric lamps. It is also useful in dyes, and in colouring glass and porcelain. Source oF TuNGsTEN—Most of the supply is obtained from wolframite ((FeMn)WO,), which is an iron-manganese tungstate due to the intergrowth of ferberite, iron tung- state, and hubnerite, manganese tungstate. A small supply

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