Roger Weller, geology instructor
email@example.com copyright 2010-R.Weller
As an exciting, colorful mineral, hornblende doesn't make the list.
Hornblende is the most common member of the amphibole family of silicate
minerals. Besides silica, it has a little bit of everything else in its chemistry: ferrous
and ferric iron, aluminum, calcium, manganese, magnesium, and alkalis.
Hornblende forms prismatic, dark brown to black, small crystals in many igneous
rocks. It is most commonly confused with the mineral augite that forms shorter,
stubby crystals. Hornblende can be distinguished from augite by its cleavage; the
two cleavage planes in augite are nearly at right angles, while the two cleavage
planes in hornblende are at an angle of 124 degrees.
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Just credit photo to R.Weller/Cochise College.