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Tumchaite crystals
© Modris Baum
Tumchaite crystals
© Modris Baum
Tumchaite crystals
© Modris Baum
Na(Zr,Sn)Si11 · 2H
Formerly UK 110, tumchaite has been recently described from the Vuoriyarvi alkali-ultrabasic massif in Russia. It seems to exhibit some pleochroism, it is colorless along Y and Z, and greenish-gray along X.
PHYSICAL CHARACTERISTICS:
Color ranges from colourless to pale orange-pink.
Luster is vitreous.
Diaphaneity: transparent to translucent.
Crystal System is monoclinic;
Crystal Habits include euhedral platy to tabular crystals forming rosettes
to 3 mm. Individual crystals average 0.8 mm across and are flattened
on [010]
Cleavage {100} is perfect.
Fracture is uneven.
Hardness is 4.5
Specific Gravity is approximately 2.78 g/cm
Streak is white.
Associated Minerals include elpidite, gaidonnayite and quartz.
Distinguishing Features the crystal habit, color and pleochroism.
Origin: Named in 2000 for the Tumcha river near the Vuoriyarvi massif
in Russia.
CLASSIFICATION:
Dana System
# 70.2.2.2
Strunz Classification
# VIII/F.34-40
REFERENCES:
AmMin 85:1516-1520 (2000)
DISTRIBUTION AND RARITY AT MONT SAINT-HILAIRE:
MSH
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