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 V. Mineral fuels

Collection:: Economics Books

MINERAL OIL 205 Ordinary oil shale has a tough leathery texture with some- times a satiny lustre. It resists weathering, so that it often stands out on cliff faces while adjacent shales break down into mud. It may be cut by a knife like tobacco, and varieties rich in oil when cut curl before the knife and are therefore known as curly shale. The richer varieties can be ignited by a match and burn freely. Microscopic examina- tion shows that the oil shale contains many vegetable re- mains, spores, grains of wax and resin; the characteristic oil producing constituents are yellow bodies which have been identified as pollen grains, alge, or spores. In many cases they are secondary bodies, often with a radial structure formed by the redeposition of cellulosic and resinous material. The working of oil shale founded the mineral oil industry. In 1847 a small seepage of petroleum in the Riddings Colliery in Derbyshire was leased by James Young but the supply soon failed. Young concluded that the oil must have been distilled from a shale, and on heating this material in a re- tort similar oil was produced. The largest supply of oil by distillation was obtained from torbanite; the first oil works was erected at Bathgate, and treated the torbanite which yielded 120 gallons to the ton. Young's patents were applied in America and many oil shale works established ; they were afterwards used as re- fineries for the oil from wells. The Scottish work had been preceded by some working of shale at Autun in Southern France. The Torbane Hill mineral was soon exhausted, and oil shales used instead; the richer seams were worked out until in later years the Scottish industry was maintained on shale which yielded less than 20 gallons of oil to the ton. After the opening of the oil wells in America the working of oil shale would have become economically impossible, but for the yield of paraffin wax and sulphate of ammonia, which have at times been more profitable than the oil. The ammonia is formed from the nitrogen in the shale. The Scottish oil shales occur in the Lower Carboniferous rocks E. of Edinburgh, and are interbedded in a series of sandstones, clays, and limestones, which include about twenty seams of worked oil shale. The beds appear to have been laid down in lagoons containing abundant fossil fish and entomostraca ; their tissues and the debris of plants which

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