Hotsonite
A variety of Minerals
What is Hotsonite?
Hotsonite is a mineral with the formula ([[Al11(PO4)2(SO4)3(OH)21.16H2O]]. The name derived from the farm Hotson 42, located 65 km west of the town of Pofadder, in Bushmanland, northwestern Cape Province, South Africa. 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.
Market Value Factors
Pricing varies for every rock and mineral, so use these universal factors to gauge Hotsonite before comparing listings or appraisals.
Size & Weight
Larger, intact specimens usually command higher prices.
Rarity & Demand
Scarce material or popular varieties sell at a premium.
Condition & Finish
Chips, repairs, and heavy wear lower value; clean prep helps.
Treatment & Provenance
Untreated specimens with documented locality are prized.
Hotsonite Localities Map
See where Hotsonite is found with a localities map, collecting zones, and geology context. Generate a sample map preview below.
Key Characteristics
Characteristics of Hotsonite
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.
Formation of Hotsonite
Hotsonite was discovered while investigating for aluminous metamorphic rocks in an abandoned sillimanite 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, Al12(SO4)5(SO4)3(OH)26.20H2O.
Composition of Hotsonite
The chemical analysis was carried out using X-ray fluorescence, and the water was calculated by the Penfield method.
Quick Facts
Physical Properties
- Color
- white
- Hardness (Mohs)
- 2.5
- Density
- 2.06 - 2.07 g/cm³
Chemical Properties
- Chemical Formula
- Al11(SO4)3(PO4)2(OH)21 · 16H2O
- Elements
- Al, H, O, P, S
Also Known As

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Hotsonite FAQs
How do I identify Hotsonite?
Hotsonite can be identified by its hardness of 2.5 on the Mohs scale, white color. Look for these key characteristics when examining specimens.
What color is Hotsonite?
Hotsonite typically appears in white. Color can vary depending on impurities and formation conditions.
How hard is Hotsonite?
Hotsonite has a hardness of 2.5 on the Mohs scale. This makes it a soft mineral that can be scratched easily.
What is the characteristics of hotsonite of Hotsonite?
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.
What is the formation of hotsonite of Hotsonite?
Hotsonite was discovered while investigating for aluminous metamorphic rocks in an abandoned sillimanite 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, Al12(SO4)5(SO4)3(OH)26.20H2O.
What is the composition of hotsonite of Hotsonite?
The chemical analysis was carried out using X-ray fluorescence, and the water was calculated by the Penfield method.


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