(Na,K)AlSi3O8
Anorthoclase is another rare mineral species at MSH.
PHYSICAL CHARACTERISTICS:
Color is usually grey (mottled).
Luster is vitreous to pearly on cleavage areas.
Diaphaneity is transparent to translucent.
Crystal System is triclinic; C.
Crystal Habits include phenocrysts.
Cleavage: {001} is perfect and {010} is good.
Fracture is conchoidal to uneven.
Hardness is 6 – 6.5
Specific Gravity is approximately 2.6 g/cm3.
Streak is white.
Associated Minerals include (??).
Distinguishing Features: Crystal habit.
Origin: Named in 1885 from the Greek an, not, plus orthos, right,
plus klan, to break, alluding to the fact that the cleavages are not
at a right angle.
CLASSIFICATION:
Dana System
# 76.1.1.6
Strunz Classification
# VIII/J.7-10
REFERENCES:
Dana 8:1607-1608 (1997)
DISTRIBUTION AND RARITY AT MONT SAINT-HILAIRE:
MSH PE AP MX SS MC HF BR SX FR
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