Gibbsite
Image: Robert M. Lavinsky (CC BY-SA 3.0)
Mineral NameGibbsite
Chemical FormulaAl(OH)3
Mohs Hardness2.5
Crystal Systemmonoclinic
Lustervitreous
Streak Colorwhite
Cleavageperfect on {001}
Fractureuneven
Specific Gravity2.35
Colorswhite, grey, greenish-white, reddish-white
Transparencytransparent
Type LocalityXianghualing Mine, Linwu County, Chenzhou Prefecture, Hunan Province, China
Mineral Grouphydroxides
Usesaluminum ore, flame retardant, smoke suppressant
Associated Mineralsboehmite, diaspore, kaolinite, goethite, hematite, quartz
Raritycommon
Description
This image displays a botryoidal aggregate of white to light grey gibbsite, forming rounded, grape-like masses with a somewhat waxy or dull luster.
Geological Context
Gibbsite is a common secondary mineral formed by the weathering of aluminum-bearing minerals in tropical and subtropical climates, often found in lateritic soils and bauxite deposits. It can also form in hydrothermal environments.
