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Phlogopite crystals
Bob Ramik sp.
Photo by Violet Anderson
© Royal Ontario Museum
Phlogopite crystals
© Stephan Wolfsried
KMgSiAlO10(F,OH)
Phlogopite, a member of the mica group is relatively uncommon at MSH. It is much rarer than the other members of the mica group.
PHYSICAL CHARACTERISTICS:
Color is usually brown; tan to gray.
Luster is vitreous to pearly.
Diaphaneity is transparent to translucent.
Crystal System is monoclinic; 2/
Crystal Habits include well-formed pseudohexagonal crystals to 5mm
and as small embedded flakes.
Cleavage {001} is perfect.
Fracture is not apparent due to cleavage.
Hardness is 2 – 2.5
Specific Gravity is approximately 2.9 g/cm
Streak is white.
Associated Minerals include albite, amphibole group, ancylite,
calcite and fluorite.
Distinguishing Features: Crystal habit and cleavage.
Origin: Named in 1841 from the Greek phlogopos, fire-like, alluding
to its common reddish tinge.
CLASSIFICATION:
Dana System
# 71.2.2b.1
Strunz Classification
# VIII/H.11-30
REFERENCES:
MinRec 21:330 (1990), Dana 8:1456-1458 (1997)
DISTRIBUTION AND RARITY AT MONT SAINT-HILAIRE:
MSH
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