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Magnesiohornblende crystals
© Modris Baum
Magnesiohornblende crystals
© Modris Baum
Ca(Mg,Fe2+Al{AlSi22}(OH)
(Alumino)magnesiohornblende, a member of the amphibole group, is uncommon at MSH. Though it easy to determine that it is an amphibole, it is very difficult to distinguish from other amphiboles.
PHYSICAL CHARACTERISTICS:
Color is usually greenish brown or black.
Luster is vitreous.
Diaphaneity is translucent.
Crystal System is monoclinic; 2/
Crystal Habits include black prisms to several millimeters.
Cleavage {110} is perfect.
Fracture is uneven to subconchoidal.
Hardness is 5 – 6.
Specific Gravity is approximately 3.2 g/cm
Streak is grayish-green.
Associated Minerals include amphibole group, analcime, biotite
and pyrite.
Distinguishing Features: Crystal habit.
Origin: Named for its composition, it is the magnesium-dominant
end-member of the hornblende group of calcic amphiboles.
CLASSIFICATION:
Dana System
# 66.1.3a.4
Strunz Classification
# VIII/F.10-40
REFERENCES:
MinRec 21:315 (1990), Dana 8:1350-1352 (1997)
DISTRIBUTION AND RARITY AT MONT SAINT-HILAIRE:
MSH
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