Soap (geology)
Soaps designate in the geology and in the Lagerstättenkunde secondary mineral enrichments in sediments such as sand or gravel , in which mineral-containing grains sorted according to their specific gravity by mechanical currents, concentrated and have then deposited. Deposits of minable concentrations of precious metals , heavy minerals or precious stones are known as soap deposits .
Emergence
Because of their weathering resistance and their high weight, the above-mentioned minerals are affected by flow conditions, e.g. B. caused by wind and water, concentrated in sediments and deposited. A distinction is made according to the type of education:
- Residual soaps that have formed on the spot due to weathering of the parent rock, in which z. B. Gold - or cassiterite - transitions are. Often only the soaps themselves are of economic importance, while the underlying mineralization is not exploitable.
- Eluvial soaps are concentrated in loose debris on slopes and embankments below the parent rock . Sometimes these soaps accumulate in existing erosion sinks in so-called pockets . Soaps also often form in the vicinity of pending chromite deposits.
- Alluvial soaps or river soaps in flowing waters were among the most important soap deposits in the past. Despite mankind's thousands of years of experience with such soaps, the exact processes of enrichment are still not fully understood today. It is a complex interplay of flow speed, sinking speed, occurrence of turbulence, specific weight and the hydraulic equivalence of the mineral grains. The most important soaps are formed during the relocation of meandering river arms, which as “dead arms” can later lie quite far away from the river.
- Beach soaps were created by the tides, ocean currents and waves.
- Marine soaps are basically created by the flooding of existing beach soaps during land subsidence or the rise in sea level.
- Aeolian soaps are blown out of desert and coastal dunes by the wind.
Occurrence
The largest known gold soap is located in the Witwatersrand near Johannesburg in South Africa - an archaic hardened uranium-containing quartz conglomerate with a base mass of pyrite , sericite and quartz .
The gold deposits on the Klondike River in Yukon , Canada are the stuff of stories and films. Gold soaps were also exploited on the Rhine , Danube , Isar , Inn , Salzach , Eder , the Thuringian Schwarza and the Saxon Göltzsch until about 100 to 150 years ago. In some cases, yield ducats were minted for representation purposes (Rhine, Isar, Inn, Danube). In more recent times (1930s, unsuccessful) and more recently attempts have been made to extract gold from gravel from quarry ponds, since the gold concentration has already increased fivefold in industrial sieving and washing processes. A pilot plant is in Balaguer in Spain and the first attempts have been promising. From a few gravel pits in the Upper Rhine Valley, some gold was and is being extracted as a by-product (Ref. 2).
An important example of residual soaps are the apatite soaps over carbonatites in Jacupiranga (Brazil), Sokli (Finland) and Sukulu (Uganda).
Much of the world's tin production comes from river soaps from the soaps in Brazil and Malaysia.
Beach soaps are the diamond soaps on the coast of Namibia, the gold soaps of Nome (Alaska) , the uranium - and thorium-containing Monazitsande in India, Australia and Brazil, the titanium-containing rutile - zircon soaps in Australia, and the magnetite soaps in New Zealand.
A larger fossil heavy mineral soap ( ilmenite and zircon ) at a depth of a few decades was discovered and examined in the 1990s southwest of Cuxhaven. There was no dismantling.
literature
- Walter L. Pohl: Mineral and energy raw materials. An introduction to the creation and sustainable use of deposits. 5th edition. Schweizerbart'sche Verlagbuchhandlung, Stuttgart 2005, ISBN 3-510-65212-6 .
- Heinrich Schurtz : The soap mining in the Ore Mountains and the whale legends . Stuttgart: Verlag von J. Engelhorn, 1890 digitized
Individual evidence
- ^ Edward J. Tarbuck, Frederick K. Lutgens: General Geology . Ed .: Pearson Education Deutschland GmbH. Munich 2009, ISBN 978-3-8273-7335-9 , pp. 781 (German edition, from the American by Tatjana D. Logan. 9th updated edition).