Harmotome

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Harmotome crystals - click for larger pic
Harmotome twin
Gary Glenn sp.
Photo by Violet Anderson
© Royal Ontario Museum

Harmotome crystals - click for larger pic
Harmotome crystals
© Doug Merson

(Ba,K)1-2(Si,Al))O16 · 6H

Harmotome is widespread in small quantities at Mont Saint-Hilaire and is indistinguishable visually from phillipsite.

PHYSICAL CHARACTERISTICS:

Color is usually colorless or white.
Luster is vitreous.
Diaphaneity is transparent to translucent.
Crystal System is monoclinic;
Crystal Habits include very small clusters of cruciform twins
or prismatic crystals on other minerals.
Cleavage {010} and {100} are distinct.
Fracture is uneven to subconchoidal.
Hardness is 4.5
Specific Gravity is approximately 2.38 g/cm
Streak is white.
Associated Minerals include aegirine, albite, amphibole group,
analcime, ancylite, calcite group, catapleiite, cordylite, elpidite,
eudialyte, fluorapatite, galena, microcline, monteregianite,
natrolite, pyrophanite and titanite.
Distinguishing Features: Crystal habit.
Origin: Named in 1801 from the Greek amos, a joint, plus tome
to cut, referring to the morphology of its twinned crystals.

CLASSIFICATION:

Dana System
# 77.1.3.5

Strunz Classification
# VIII/J.25-70

REFERENCES:
MinRec 21:314 (1990), Dana 8:1664-1665 (1997)

DISTRIBUTION AND RARITY AT MONT SAINT-HILAIRE:

MSH
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