Amphibole
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Amphibole is a group of inosilicate minerals, forming prism or needlelike crystals, composed of double chain SiO4 tetrahedra, linked at the vertices and generally containing ions of iron and/or magnes
Amphibole (tremolite)
Photomicrographs of a thin section containing an amphibole crystal; under cross-polarized light on the left, and plane-polarized light on the right.
![Double-chain inosilicate structure looking up the [100] axis. Silicon ions are hidden by apical oxygen ions.](https://upload.wikimedia.org/wikipedia/commons/thumb/d/d5/Amphibole_100.jpg/500px-Amphibole_100.jpg)
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.](https://upload.wikimedia.org/wikipedia/commons/thumb/b/b7/Amphibole_010.jpg/500px-Amphibole_010.jpg)
Side view (along [010]) of double chain inosilicate backbone. Apical oxygens are at the bottom.
Hornblende
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Hornblende is a complex inosilicate series of minerals. It is not a recognized mineral in its own right, but the name is used as a general or field term, to refer to a dark amphibole. Hornblende miner
Amphibole
…of the more evolved magmas favors formation of amphiboles rather than pyroxenes. The highest amphibole content, around 20%, is found in andesites. Hornblende is widespread in igneous and metamorphic rocks and is particularly common in syenites and diorites. Calcium is sometimes a constituent of naturally…
Hornblende crystal (dark green) about 35 mm long, with apatite (white)
Ferrohornblende, near Bilin, Bohemia, Czech Republic
Hornblende diorite from the Henry Mountains, Utah, US
Ordovician hornblende schist near Marlboro, Vermont. The black sprays are hornblende amphibole.