Gobbinsite
Na₄(Ca,Mg,K₂)Al₆Si₁₀O₃₂ · 12H₂O

     Gobbinsite is a very rare member of the zeolite group and is an extremely rare occurrence at Mont Saint-Hilaire. MSH was the first known locality for crystallized specimens.

PHYSICAL CHARACTERISTICS:

Color is usually white to tan.
Luster is vitreous to dull to greasy.
Diaphaneity: transparent.
Crystal System is tetragonal; P4₁2₁2.
Crystal Habits include spike-like, pyramidal crystals to 2mm.
   Crystals are deeply etched and show no prism faces.
Cleavage none observed.
Fracture not observed.
Hardness is approximately 4.
Specific Gravity is approximately 2.2 g/cm³.
Streak is white.
Associated Minerals include aegirine, eudialyte, microcline,
   natrolite, philipsite and sérandite.
Distinguishing Features: Crystal habit and etching.
Origin: Named in 1982 for its discovery locality, south of the
   Gobbins area, Magee Island, Antrim County, Northern Ireland.

CLASSIFICATION:

REFERENCES:
MinRec 21:312 (1990), Dana 8:1663-1664 (1997)

DISTRIBUTION AND RARITY AT MONT SAINT-HILAIRE:

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