Gmelinite-Na – Saint-Hilaire

(NaCa)AlSi₁₂ · 6H

Gmelinite-Na, a member of the zeolite group, is moderately common at Mont Saint-Hilaire. Formerly simply known as gmelinite, recent analysis following the new nomenclature recommendations for zeolites from the IMA add the suffix -Na for MSH.

PHYSICAL CHARACTERISTICS:

Color is usually colorless, pale yellow, lemon-yellow, orange
and pale green.
Luster is vitreous to dull.
Diaphaneity is transparent to translucent.
Crystal System is hexagonal; mmc
Crystal Habits include excellent thin hexagonal plates to 5mm,
complex groups of plates forming attractive rosettes and spherical
aggregates; short hexagonal prisms terminated by hexagonal
pyramids and basal pinacoids.
Cleavage {010} is distinct and {001} shows parting.
Fracture is uneven.
Hardness is 4.5.
Specific Gravity is approximately 2.1 g/cm
Streak is white.
Associated Minerals include dolomite, hematite, microcline,
molybdenite, pyrite, pyroxene group, quartz, rutile and siderite.
Distinguishing Features: Crystal habit, color and twinning.
Origin: Named in 1825 for Christian Gottlob Gmelin (1792-1860),
Professor of Chemistry, University of Tübingen, Germany.

CLASSIFICATION:

Dana System
# 77.1.2d.1

Strunz Classification
# VIII/J.26-50

REFERENCES:
MinRec 21:312 (1990), Dana 8:1657-1659 (1997)

DISTRIBUTION AND RARITY AT MONT SAINT-HILAIRE:

MSH
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Legend

Gmelinite-Na crystals - click for larger pic
Gmelinite-Na crystals
© Doug Merson