Monteregianite-(Y) (TL)

(Na,K)(Y,Ca)Si1638 · 10H

Mont Saint-Hilaire is the type locality for monteregianite-(Y) and still the only locality.

PHYSICAL CHARACTERISTICS:

Color ranges from colorless, pale to dark gray, pale rose or violet, and
white to nearly black. Some crystals are zoned pink or green.
Luster is vitreous (colorless, rose and violet) or greasy to silky for the
others.
Diaphaneity is transparent (colorless, rose and violet) and the others
are translucent to opaque.
Crystal System is monoclinic (pseudo-orthorhombic);
Crystal Habits include well formed, sharp, tabular or lath-shaped
crystals forming attractive radiating sprays, parallel stacked groups
and aggregates.
Cleavage {010} is perfect, {001} is very good and {100} is fair.
Fracture (??).
Hardness is 3.5
Specific Gravity is approximately 2.4g/cm
Streak is white.
Associated Minerals include aegirine, albite, amphibole group,
apophyllite series, arfvedsonite, ashcroftine, astrophyllite, calcite,
catapleiite, donnayite, elpidite, ewaldite, fluorite, genthelvite,
harmotome, labuntsovite, lorenzenite, microcline, molybdenite,
narsarsukite, natrolite, nenadkevichite, pectolite, phlogopite,
polylithionite, pyrite, quartz, rhodochrosite, sepiolite, sphalerite,
steacyite and titanite.
Distinguishing Features: Intense green fluorescence under SW.
Origin: Named in 1978 for the Monteregian Hills, which include
the type locality.

CLASSIFICATION:

Dana System
# 72.5.1.2

Strunz Classification
# VIII/H.38-10

REFERENCES:
CanMin 16:561-565 (1978), AmMin 72:365-374 (1987),
MinRec 21:323 (1990), Dana 8:1539-1540 (1997)

DISTRIBUTION AND RARITY AT MONT SAINT-HILAIRE:

MSH
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Legend

Monteregianite-(Y) crystals - click for larger pic
Monteregianite-(Y) crystals
© Stephan Wolfsried

Monteregianite-(Y) crystals - click for larger pic
Monteregianite-(Y) crystals
© Bill Lechner

Monteregianite-(Y) crystals - click for larger pic
Monteregianite-(Y) crystals
© Jason B. SMith