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Muscovite
KAl2(Si3Al)O10(OH,F)11

     Muscovite, a member of the mica group, is uncommon at MSH. It is hard to distinguish from the other members of the mica group.

PHYSICAL CHARACTERISTICS:

Color ranges from pale yellow to pale green, colorless and light brown.
Luster is vitreous to pearly.
Diaphaneity is transparent to translucent.
Crystal System is monoclinic; C2/c.
Crystal Habits include small plates and short pseudohexagonal prisms,
   intergrown clusters, globular aggregates and embedded masses.
Cleavage {001} is perfect.
Fracture is not apparent due to cleavage.
Hardness is 2.5 - 3.5
Specific Gravity is approximately 2.8 g/cm3.
Streak is white.
Associated Minerals include albite, anatase, ancylite, beryl, calcite,
   chlorite group, dolomite, magnesite, marcasite, pyrite, pyrrhotite,
   quartz, siderite and UK # 56.
Distinguishing Features: Crystal habit.
Origin: Named in 1850 and is derived from its use in windows as
    muscovy glass, Muscovy being an old Russian Province.

CLASSIFICATION:

Dana System
# 71.2.2a.1

Strunz Classification
# VIII/H.10-30

REFERENCES:
MinRec 21:324 (1990), Dana 8:1448-1451 (1997)

DISTRIBUTION AND RARITY AT MONT SAINT-HILAIRE:

MSH
¤¤¤

PE
--

AP
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MX
¤¤

SS
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MC
--

HF
¤¤

BR
--

SX
--

FR
--

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