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

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Penkvilksite
Na4Ti2Si8O22 · 5H2O

     Penkvilksite is extremely rare at Mont Saint-Hilaire. It was first found at the quarry in 1975 and designated UK #41.

PHYSICAL CHARACTERISTICS:

Color is usually colorless and pale gray to white.
Luster is porcelaneous; dull to silky on fractures.
Diaphaneity is transparent to translucent.
Crystal System is orthorhombic or monoclinic; (?).
Crystal Habits include clusters of tabular prismatic crystals to 1.5mm;
   rosettes and spherical aggregates of lamellar crystals to 1mm.
Cleavage is perfect in one direction.
Fracture is uneven.
Hardness is 5.
Specific Gravity is approximately 2.58 g/cm3.
Streak is white.
Associated Minerals include aegirine, ancylite, apophyllite series,
   calcite, catapleiite, monteregianite, nenadkevichite, pectolite,
   tadzhikite and vesuvianite.
Distinguishing Features: Crystal habit.
Origin: Named in 1964 from the Lapp penk, curly, plus vilkis, white,
   referring to its habit and color.

CLASSIFICATION:

Dana System
# 70.2.2.1

Strunz Classification
# VIII/F.34-30

REFERENCES:
MinRec 21:329 (1990), Dana 8:1400-1401 (1997)

DISTRIBUTION AND RARITY AT MONT SAINT-HILAIRE:

MSH
¤¤¤

PE
¤¤

AP
--

MX
¤¤

SS
--

MC
--

HF
--

BR
--

SX
--

FR
--

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