Amphibole

Amphibole is a group of inosilicate minerals. They form prism or needlelike crystals.^[1]

They are double chain SiO₄ tetrahedra, linked at the vertices. Usually they contain ions of iron and/or magnesium in their structures. Amphiboles can be green, black, colorless, white, yellow, blue, or brown.^[2]

Amphibole Media

Photomicrographs of a thin section containing an amphibole crystal; under cross-polarized light on the left, and plane-polarized light on the right.
Mineral assemblage of igneous rocks
Hornblende diorite from the Henry Mountains, Utah, US
Amphibolite from Warrensburg, Adirondack Mountains, New York State, USA
Double-chain inosilicate structure looking up the [100] axis. Silicon ions are hidden by apical oxygen ions.
Side view (along [010]) of double chain inosilicate backbone. Apical oxygens are at the bottom.
Amphibole structure looking along the [001] axis. Silicon ions are emphasized. Two "I-beams" are outlined in green.

References

↑ "Amphibole". Dictionary of Geology. Retrieved 2013-01-21.
↑ Mindat, Amphibole Supergroup

[1] "Amphibole". Dictionary of Geology. Retrieved 2013-01-21.

[2] Mindat, Amphibole Supergroup

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