Steacyite (Type Locality)
K_0.6-0.8(Ca,Na)₂ThSi₈O₂₀

     Steacyite is a rare accessory mineral at MSH. It, mistakingly, carried the name of ekanite until 1982, when the mineral was redefined and renamed.

PHYSICAL CHARACTERISTICS:

Color ranges from dark gray, grayish brown, off-white, beige and pale
   brown to dark brown.
Luster is vitreous to greasy or dull.
Diaphaneity is translucent to opaque.
Crystal System is tetragonal; P4/mcc.
Crystal Habits include sharp tetragonal prisms to 3mm, sometimes as
   attractive cruciform twins; rarely as embedded crude prisms, square
   tabular crystals; foliated spherical aggregates and as compact chalky
   spherical aggregates.
Cleavage none observed.
Fracture is irregular.
Hardness is 5.
Specific Gravity is approximately 2.95 g/cm³.
Streak is white.
Associated Minerals include aegirine, albite, analcime, calcite,
   epididymite, eudialyte, fluorite, microcline, monteregianite, natrolite,
   nenadkevichite, polylithionite, raite and yofortierite.
Distinguishing Features: Crystal habit and twins.
Origin: Named in 1982 after Harold Robert Steacy (b. 1923), curator,
   Canadian National Mineral Collection, Geological Survey of Canada.

CLASSIFICATION:

REFERENCES:
CanMin 20:59-63 (1982), MinRec 21:339-340 (1990), Dana 8:1269 (1997)

DISTRIBUTION AND RARITY AT MONT SAINT-HILAIRE:

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