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Sasaite, a new phosphate mineral from West Driefontein Cave, Transvaal, South Africa

Published online by Cambridge University Press:  05 July 2018

J. Martini*
Affiliation:
Geological Survey of South Africa, private bag × 112, Pretoria, South Africa

Summary

A new mineral, sasaite, occurs as white chalky nodules in the soil of a dolomitic cave and seems to be derived from the action of bat guano on clay minerals. Under the microscope it consists of an agglomeration of plates 10–20 µm on greatest dimension and with a rhombic shape. Its formula is (Al, Fe3+)14(PO411(OH)7SO4·83H2O and it is orthorhombic or quasi-orthorhombic. Preliminary crystallographic data based on an orthorhombic cell are a 21·50, b 30·04, c 92·06 Å, Z10, based on a calculated density of 1·747 (observed 1·75). The optical indices are α 1·465, β 1·473, γ 1·477 all ±0·001, and the principal vibration directions are parallel or quasi-parallel to the crystallographic axis.

Type
Research Article
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1978

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References

Bridge, (P. J.), 1973. Mineral. Mag. 39, 467-9.CrossRefGoogle Scholar
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