Home > Mineral Descriptions > Thornasite (TL)



Thornasite (Type Locality)
(Na,K)ThSi11(O,F,OH)25 · ยท 8H2O

     Thornasite was described from Mont Saint-Hilaire in 1987. Its occurs extremely rarely and it fluoresces very bright green under SW and LW.

PHYSICAL CHARACTERISTICS:

Color is usually colorless or very pale green.
Luster is vitreous to silky, greasy or dull.
Diaphaneity is transparent to translucent.
Crystal System is hexagonal; R32.
Crystal Habits include embedded anhedral crystals and irregular
   grains to 0.7mm.
Cleavage none observed.
Fracture is subconchoidal to uneven.
Hardness is not measured.
Specific Gravity is approximately 2.6 g/cm3.
Streak is white.
Associated Minerals include albite, analcime, calcite, catapleiite,
   epididymite, eudialyte, leifite, mangan-neptunite, microcline,
   natrolite, polylithionite, sérandite, steacyite and yofortierite.
Distinguishing Features: Color and mineral associations.
Origin: Named in 1987 for its composition; thorium, sodium and
   silicon (Thor + Na + S + ite), formerly designated as UK #27.

CLASSIFICATION:

Dana System
# 72.1.2.1

Strunz Classification
# VIII/D.20-10

REFERENCES:
CanMin 25:181-183 (1987), MinRec 21:342-343 (1990),
Dana 8:1521-1522 (1997)

DISTRIBUTION AND RARITY AT MONT SAINT-HILAIRE:

MSH
¤¤¤

PE
--

AP
¤¤

MX
--

SS
--

MC
--

HF
--

BR
--

SX
--

FR
--

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