Hornblende
Real mineral · common · (Ca,Na)₂(Mg,Fe,Al)₅(Si,Al)₈O₂₂(OH)₂
The most common amphibole mineral, forming dark crystals in a wide range of igneous and metamorphic rocks. Its complex composition varies significantly between specimens. A major constituent of diorite and andesite.
Identity
- Formula
- (Ca,Na)₂(Mg,Fe,Al)₅(Si,Al)₈O₂₂(OH)₂
- Chemical class
- silicate
- Mineral group
- Actinolite, Richterite, Tremolite
Crystallography
- Crystal system
- monoclinic
- Habits
- prismatic, bladed, massive
- Fracture
- subconchoidal
Physical properties
- Mohs hardness
- 5.5
- Density
- 3.2 g/cm³
- Luster
- vitreous, silky
- Colors
- dark green, black, brownish black
- Streak
- gray-green
- Transparency
- opaque, translucent
Geology
- Origins
- igneous, metamorphic
- Host rocks
- granite, diorite, schist, gneiss
- Associated minerals
- feldspar, Quartz, Mica, pyroxene
- Geography
- worldwide
Classification
- Rarity
- common
- Gem quality
- No
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