Hornblende
Hornblende group
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
- Members
- Ferro-hornblende, Magnesio-hornblende
- Mineral group
- Actinolite, Nephrite, 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
- pale gray-green
- Transparency
- Translucent, Opaque
Geology
- Origins
- Igneous, Metamorphic
- Host rocks
- Granite, Schist and gneiss
- Associated minerals
- feldspar, Quartz, biotite, pyroxene
- Found in
- Andesite, Diorite, Gabbro, Granite, Rhyolite
- Geography
- worldwide
Classification
- Rarity
- Common
- Gem quality
- No
Sources
- Hornblende. Mindat.org (Hudson Institute of Mineralogy).
- M. Pasero and others, IMA Commission on New Minerals, Nomenclature and Classification, The New IMA List of Minerals, updated September 2026. International Mineralogical Association (CNMNC), 2026.
- J. W. Anthony, R. A. Bideaux, K. W. Bladh, M. C. Nichols, Magnesio-hornblende. Mineral Data Publishing, Handbook of Mineralogy, 2001.
- Ferro-hornblende: Mineral information, data and localities. mindat.org.
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