Amphibolite
Image: <a href="//commons.wikimedia.org/wiki/User:Strekeisen" title="User:Strekeisen">Strekeisen</a> (CC BY-SA 4.0)
Mineral NameAmphibolite
Chemical Formula(Ca,Na)2-3(Mg,Fe,Al)5(Al,Si)8O22(OH)2
Mohs Hardness5
Crystal Systemmonoclinic
Streak Colorwhite to light gray
Cleavageperfect in two directions at ~56° and ~124°
Fractureuneven to conchoidal
Specific Gravity3
Colorsblue, green, yellow, orange, purple, dark green, black
Transparencytranslucent
Type LocalityWorldwide
Mineral GroupMetamorphic Rock
Usesconstruction aggregate, dimension stone
Associated Mineralshornblende, plagioclase feldspar, garnet, epidote, quartz, biotite
Raritycommon
Description
This image displays a thin section of amphibolite under crossed nicols with a compensator, revealing a vibrant mosaic of interlocking hornblende crystals exhibiting striking interference colors ranging from blues and greens to yellows, oranges, and purples, characteristic of its metamorphic texture.
Geological Context
Amphibolite is a medium- to coarse-grained metamorphic rock formed under high pressure and temperature conditions, typically from the regional metamorphism of mafic igneous rocks or argillaceous sedimentary rocks, defining the amphibolite facies.
