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Thorbastnäsite crystals - click for larger pic
Thorbastnäsite crystals
© Modris Baum

Thorbastnäsite crystals - click for larger pic
Thorbastnäsite crystals
© Modris Baum

Thorbastnäsite crystals - click for larger pic
Thorbastnäsite crystals
© Stephan Wolfsried

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Home > Mineral Descriptions > Thorbastnäsite - (3 Photos)



Thorbastnäsite
Th(Ca,Ce)(CO3)2 · H2O

     Mont Saint-Hilaire is the third world occurrence for this exceptionally rare species. The Francon quarry on Montreal island was the first Canadian occurrence. Dana's New Mineralogy, 8th edition and several sources only indicated two occurrences for this species. It is found in vuggy matrix, occasionally with an unidentified brownish black micro hydrocarbon coating.

PHYSICAL CHARACTERISTICS:

Color is usually white.
Luster is vitreous.
Diaphaneity: translucent to opaque.
Crystal System is hexagonal; P62c.
Crystal Habits include small prismatic crystals.
Cleavage {1010} is indistinct, distinct to perfect parting on {0001).
Fracture is uneven.
Hardness is 4 - 4.5
Specific Gravity is approximately 4.04 g/cm3.
Streak is white.
Associated Minerals include donnayite.
Distinguishing Features: Crystal habits.
Origin: Named in 1965 for the compositional and crystal structural
   ressemblance to the bastnäsite group.

CLASSIFICATION:

Dana System
# 16b.1.2.1

Strunz Classification
# V/E.10-10

REFERENCES:
Dana 8:499 (1997)

DISTRIBUTION AND RARITY AT MONT SAINT-HILAIRE:

MSH
¤¤¤

PE
¤¤

AP
--

MX
--

SS
--

MC
--

HF
--

BR
--

SX
--

FR
--

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