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Epistolite crystals
© Doug Merson
Epistolite crystals
© Stephan Wolfsried
NaNbTi(Si(OH) · 4H
Epistolite is moderately rare at MSH. It was originally thought to be murmanite. A new formula for epistolite was recently published in the Canadian Mineralogist, Volume 42, pages 797-806 (2004).
PHYSICAL CHARACTERISTICS:
Color is tan, silvery, pinkish beige and yellow-gray.
Luster is vitreous and pearly to silky on lamellar habit.
Diaphaneity is translucent and opaque on lamellar habit.
Crystal System is triclinic; 1.
Crystal Habits include sharp well-formed platy crystals to 5cm
and embedded lamellar to micaceous masses.
Cleavage {100} is perfect.
Fracture is uneven.
Hardness is 2 – 3.
Specific Gravity is approximately 2.8 g/cm
Streak is white.
Associated Minerals include aegirine, albite, analcime, eudialyte,
microcline and nenadkevichite.
Distinguishing Features: Crystal habit and color.
Origin: Named in 1897 from the Greek epistole, letter, in allusion
to its white color and flat, rectangular habit.
CLASSIFICATION:
Dana System
# 56.2.7.1
Strunz Classification
# VIII/E.7-190
REFERENCES:
MinRec 21:308 (1990), Dana 8:1176-1177 (1997)
DISTRIBUTION AND RARITY AT MONT SAINT-HILAIRE:
MSH
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