(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:

REFERENCES:
Dana 8:1607-1608 (1997)

DISTRIBUTION AND RARITY AT MONT SAINT-HILAIRE:

MSH          PE          AP          MX          SS           MC          HF           BR          SX          FR
¤¤¤            —             —             —             —               —             —              —             —             —  

Legend