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Tetranatrolite or Gonnardite (??)
© Marc Favre
NaAlSi10 · 2H
Do NOT discredit Tetranatrolite yet. A recent paper in the American Mineralogist has called for the discreditation of tetranatrolite in favour of gonnardite. The paper could validate tetranatrolite as gonnardite for all but 4 locations, of which MSH is one. Another paper, soon to be published, on the crystal structure of tetranatrolite seems to validate the species.
PHYSICAL CHARACTERISTICS:
Color is white.
Luster is silky to dull.
Diaphaneity is mostly opaque and rarely translucent.
Crystal System is tetragonal; 42
Crystal Habits include small prisms, fibrous sprays and coatings
on natrolite.
Cleavage: none observed.
Fracture is (??).
Hardness is 5.
Specific Gravity is approximately 2.3 g/cm
Streak is white.
Associated Minerals include aegirine, amphibole group, analcime,
ancylite-(Ce), microcline, monteregianite-(Y), narsarsukite and
natrolite.
Distinguishing Features: epitactic relationship with natrolite.
Origin: Named in 1980 for the symmetry (tetragonal) and natrolite.
CLASSIFICATION:
Dana System
# 77.1.5.2
Strunz Classification
# VIII/J.21-30
REFERENCES:
CanMin 18:77-84 (1980), MinRec 21:342 (1990), Dana 8:1679-1680 (1997), AmMin 84:1445-1450 (1999)
DISTRIBUTION AND RARITY AT MONT SAINT-HILAIRE:
MSH
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