Hotsonite is a mineral whose name derives from the farm Hotson 42, located 65 km west of the town of

Pofadder Pofadder is the Afrikaans name for Bitis arietans, puff adder (snake). Pofadder may also refer to: * Pofadder, Northern Cape, a small town in South Africa * Pofadder (food), a traditional South African food made from the same ingredients as Skilpa ...

, in

Bushmanland Bushmanland (Boesmanland in Afrikaans) may refer to: * Bushmanland (South West Africa), a bantustan in South West Africa (present-day Namibia) * Bushmanland, Northern Cape Bushmanland is an arid area south of the Orange River and west of Ke ...

, northwestern

Cape Province The Province of the Cape of Good Hope (), commonly referred to as the Cape Province () and colloquially as The Cape (), was a province in the Union of South Africa and subsequently the Republic of South Africa. It encompassed the old Cape Co ...

South Africa South Africa, officially the Republic of South Africa (RSA), is the Southern Africa, southernmost country in Africa. Its Provinces of South Africa, nine provinces are bounded to the south by of coastline that stretches along the Atlantic O ...

. This is an arid region with an average rainfall of 3 inches per annum. The name was approved by the Commission on New Minerals and Mineral Names of the International Mineralogical Association (July 1983) It is chemically related to sanjuanite and kribergite.

Discovery and occurrence

Hotsonite was discovered while investigating for aluminous metamorphic rocks in an abandoned

sillimanite Sillimanite or fibrolite is an aluminosilicate mineral with the chemical formula Al2SiO5. Sillimanite is named after the American chemist Benjamin Silliman (1779–1864). It was first described in 1824 for an occurrence in Chester, Connecticut ...

quarry in 1982. The two senior authors sampled peculiar veins and encrustations of cryptocrystalline fine-grained white material. One of the materials had properties which could not be matched to any known mineral. The mineral occurs closely with

zaherite Zaherite is a mineral, a complex sulfate of aluminium, formula Al12( O H)26( SO4)5·20 H2O. It was discovered in the Salt range, Punjab, Pakistan by M. A. Zaher of the Bangladesh Geological Survey after whom it is named in 1977. This mineral would ...

, Al₁₂(SO_4)₅(SO_4)₃(OH)₂₆.20H₂O.

Physical properties

Hotsonite's physical properties are similar to other hydrated aluminous sulfates and some phosphates. It occurs as a white chalk like mineral with a dull to silky luster, and an earthy fracture. When observed under magnification of 500 times, it has a flaky appearance. Hotsonite appears with a white coloration, and small grain size. The Mohs hardness is 2.5, and with a density value of 2.060 to 2.068.

Chemical composition

The chemical analysis was carried out using X-ray fluorescence, and the water was calculated by the Penfield method.

Diffraction information

Powder diffraction used for hotsonite data:

References

{{Reflist Phosphate minerals Sulfate minerals Aluminium minerals Triclinic minerals Minerals in space group 2