Rostite
Rostite is a rare sulfate mineral with the chemical formula aluminum sulfate hydroxide pentahydrate, AlSO4(OH)·5H2O. It crystallizes in the orthorhombic crystal system and belongs to the Strunz classification 7.DB.10. This mineral is characterized by its soft, low hardness on the Mohs scale, a relatively low density, and a vitreous to pearly luster. It typically appears white to colorless and is classified as a hydrous sulfate mineral. Rostite is notable for its high water content and is often found in secondary mineral assemblages.
Composition
- OOxygen69.5%
- SSulfur13.9%
- AlAluminium11.7%
- HHydrogen4.8%
Overview
Rostite is a rare sulfate mineral with the chemical formula aluminum sulfate hydroxide pentahydrate, AlSO4(OH)·5H2O. It crystallizes in the orthorhombic crystal system and belongs to the Strunz classification 7.DB.10. This mineral is characterized by its soft, low hardness on the Mohs scale, a relatively low density, and a vitreous to pearly luster. It typically appears white to colorless and is classified as a hydrous sulfate mineral. Rostite is notable for its high water content and is often found in secondary mineral assemblages.
Etymology
Rostite is named after Rudolf Rost, a German mineralogist. The mineral was redefined by the International Mineralogical Association, but the specific year of its naming or redefinition is not provided in the facts.
How to recognize it
Rostite can be identified by its low hardness, which is below 3 on the Mohs scale, and its white to colorless color. It has a vitreous to pearly luster and a low density. The streak is typically white. Due to its softness and hydrous nature, it may be confused with other soft sulfate or hydroxide minerals, but its specific chemical composition and crystal system help distinguish it.
Trivia
Rostite is notable for its high water content, which contributes to its hydrous chemical structure. It is a rare mineral, and its redefinition by the IMA highlights its unique classification. The mineral is named after Rudolf Rost, honoring a significant figure in mineralogy.