Steacyite (TL) – Saint-Hilaire

_0.6-0.8(Ca,Na)ThSi₂₀

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; 4/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/cm
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:

Dana System
# 63.1.1.1

Strunz Classification
# VIII/E.10-30

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

DISTRIBUTION AND RARITY AT MONT SAINT-HILAIRE:

MSH
¤¤¤

Legend