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Epidote crystals - click for larger pic
Epidote crystals
Photo by Doug Merson
© Doug Merson

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Epidote
Ca2(Fe3+, Al)3(SiO4)(Si2O7)(O,OH)2

     The occurrence of epidote, a member of the epidote group, is rare at MSH.

PHYSICAL CHARACTERISTICS:

Color varies from dark brown to red-brown to black.
Luster is vitreous to greasy.
Diaphaneity is opaque.
Crystal System is monoclinic; P21/m.
Crystal Habits include the short prismatic crystals to 3mm.
Cleavage {001} is imperfect, {100} and {110} are poor.
Fracture is conchoidal to uneven.
Hardness is 5.5 - 6.
Specific Gravity is approximately 3.4 g/cm3.
Streak is gray.
Associated Minerals include aegirine, allanite, calcite, fluorite,
   grossular, microcline, prehnite, pyrrhotite and titanite.
Distinguishing Features: Crystal habit and luster.
Origin: Named in 1801 from the Greek epidosis, increase, because
   the base of the rhombohedral prism has one side longer than
   the other.

CLASSIFICATION:

Dana System
# 58.2.1a.7

Strunz Classification
# VIII/C.23-20

REFERENCES:
MinRec 21:308 (1990), Dana 8:1200-1201 (1997)

DISTRIBUTION AND RARITY AT MONT SAINT-HILAIRE:

MSH
¤¤¤

PE
--

AP
--

MX
¤¤

SS
--

MC
--

HF
¤¤

BR
--

SX
--

FR
--

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