Andesine
Image: Robert M. Lavinsky (CC BY-SA 3.0)
Mineral NameAndesine
Chemical Formula(Na,Ca)Al(Si,Al)3O8
Mohs Hardness6
Crystal Systemtriclinic
Lustervitreous
Streak Colorwhite
Cleavageperfect on {001} and {010}, intersecting at nearly 90 degrees
Fractureuneven
Specific Gravity2.67
Colorswhite, gray, reddish, green, yellow
Transparencytransparent
Type LocalitySilberberg Mine, Bodenmais, Lower Bavaria, Bavaria, Germany
Mineral GroupSilicates (Tectosilicates, Feldspar Group, Plagioclase Series)
Usesgemstone, collector
Associated Mineralsquartz, cordierite, garnet, other feldspars
Rarityuncommon
Description
This specimen features a reddish-orange, somewhat blocky crystal of andesine, possibly displaying some cleavage faces, embedded within a darker matrix.
Geological Context
Andesine is a common rock-forming mineral found in intermediate igneous rocks like diorite and andesite, and in some metamorphic rocks. This specific specimen comes from a polymetamorphic iron sulphide deposit hosted in cordierite-garnet gneiss, disseminated by quartz veins.
