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Hornblende  Pictures

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A cleavage fragment of "Hornblende".

  A prismatic crystal of "Hornblende" with the top view to the right.

The diamond shaped cross section of "Hornblende" in a granitic pegmatite.

HORNBLENDE is not a recognized mineral name but is included in this archive because of its common usage.  The mineral described as hornblende is a member of the Amphibole group.

CHEMISTRY Na,Ca₂(mg,Fe,Al)₅(OH)₂(Si,Al)₈O₂₂ 

CRYSTALLOGRAPHY Monoclinic 

CRYSTAL GROWTH AND HABITS Hornblende crystals are prismatic to columnar, stubby blocky, fibrous and fine to coarse grained.  Crystals typically have a diamond shaped cross section.

COLOR AND OTHER OPTICAL PROPERTIES Black, brown to dark green, translucent to opaque 

HARDNESS 6        

SPECIFIC GRAVITY 3.0 - 3.4        

LUSTER Vitreous to sub vitreous     

STREAK White

BREAKABILITY Hornblende has good cleavage in 2 directions (56^o and 124^o) producing diamond shaped cross sections.  It also has an uneven fracture and is brittle.  

OCCURRENCE Hornblende is widespread through igneous and metamorphic rocks, especially amphibolites. 

ASSOCIATED MINERALS - Quartz, Feldspars, Muscovite, Biotite, Garnets