Microcrystalline sphalerite in resin globules suspended in Lake Kivu, East Africa

E.T. Degens; H. Okada; S. Honjo; J.C. Hathaway

doi:10.1007/bf00206891

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Microcrystalline sphalerite in resin globules suspended in Lake Kivu, East Africa

E.T. Degens·H. Okada·S. Honjo·J.C. Hathaway

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Abstract

The origin and chemical nature of micron-sized spheres found as suspended particles in Lake Kivu are examined. It can be shown that the hollow spheres, with a wall thickness of 500 Å, consist of a complex polymeric resinous material which has little functionality, except for hydroxyl groups. The spheres arise in the process of degassing of water samples at depth. Tiny gas bubbles, about 1 micron in size, act as scavengers of dissolved resinous material. The newly created resinous membrane promotes the selective coordination of zinc dissolved in the water column. In the prevailing H 2 S regime, formation of sphalerite crystals in induced. The size range of the crystals, 5 to 50 Å, corresponds to 1 to 10 unit cells and suggests that the resinous membrane also acts as a template in sphalerite growth processes. The sources of the zinc and dissolved gases (CO 2 , CH 4 , H 2 S) are hydrothermal springs seeping from the lake bottom into the basin. Water discharge is substantial; about 100 years are required to fill the lake to its present level (ca. 550 km 3 water). The average Kivu water contains 2 ppm zinc. Thus, 1 million tons of zinc are contained in Lake Kivu in the form of sphalerite.

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Source-reported bounding extent: -2.58640142780824° to -1.491225656518564° latitude; 28.707275390624996° to 29.53125° longitude. This indicates report coverage, not an exact sampling location. View area on OpenStreetMap.

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E.T. Degens, H. Okada, S. Honjo, J.C. Hathaway. 1972. Microcrystalline sphalerite in resin globules suspended in Lake Kivu, East Africa. https://doi.org/10.1007/bf00206891

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