Ca₃Al₂(SiO₄)₃

Andradite, a member of the garnet mineral species, occurs at MSH in miaroletic cavities and rarely in marble xenoliths.

PHYSICAL CHARACTERISTICS:

Color is usually dark to pale-olive green, brownish green and
yellow-green.
Luster is vitreous.
Diaphaneity is translucent to opaque.
Crystal System is isometric; Ia3d.
Crystal Habits include sharp dodecahedra to 8mm and small
clusters of crystals.
Cleavage: none observed.
Fracture is subconchoidal.
Hardness is 6.5 – 7.5
Specific Gravity is approximately 3.8 g/cm³.
Streak is white.
Associated Minerals include barite, grossular, pectolite and
sodalite.
Distinguishing Features: Crystal habit and luster.
Origin: Named in 1868 for Jose Bonifacio de Andrada e Silva
(1763-1838), Brazilian statesman and geologist who first
examined and described the mineral.

CLASSIFICATION:

REFERENCES:
MinRec 21:296 (1990), Dana 8:1044-1046 (1997)

DISTRIBUTION AND RARITY AT MONT SAINT-HILAIRE:

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