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Formula: CaZrSi3O9.3H2O
Cyclosilicate (ring silicate), hilairite group,
zirconium-bearing mineral
Crystal System: Trigonal
Specific gravity: 2.68 measured
Hardness: 4
Streak: White
Colour: White to pale blue
Luminescence: Not fluorescent under UV
Common impurities: Na,Cu,Al,Fe,Ti
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Environments
Localities
At the Demix-Varennes quarry, Saint-Amable sill, Varennes & St-Amable, Lajemmerais RCM, Montérégie, Quebec, Canada,
calciohilairite occurs in miarolitic cavities in a
nepheline syenite sill. Associated minerals include
nenadkevichite,
rhodochrosite,
polylithionite, fluorite,
aegirine, astrophyllite,
eudialyte, microcline,
manganoneptunite and pyrite
(HOM).
At the type locality, Washington Pass, Golden Horn Batholith, Okanogan County, Washington, USA,
calciohilairite has been found in two occurrences in boulders of border
granite on a talus slope on the north side of Liberty Bell Mountain.
The first occurrence consisted of white altered trigonal prismatic crystals up to 2 mm associated with
microcline, quartz,
albite, fluorite and
chlorite in a zone of small miarolitic cavities.
The second occurrence consisted of smaller (up to 1 mm) white to pale blue unaltered crystals in a larger isolated
miarolitic cavity associated with microcline,
quartz, albite,
bastnäsite, zircon,
chlorite and malachite.
Other minerals found in miarolitic cavities in the border granite in
the same area but not associated with calciohilairite include
allanite, kainosite,
gadolinite and
clinofergusonite
(AM 73.1191-1194).
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