Rhodochrosite – Saint-Hilaire

MnCO

At Mont Saint-Hilaire, rhodochrosite is a common late-stage mineral in pegmatites and altered pegmatites. Some crystals up to 10cm have been found, however, these large crystals are generally with unattractive coloration and transparency.

PHYSICAL CHARACTERISTICS:

Color ranges from very pale pink, pale to deep red, orange-red,
brownish red, orange-brown, pale to dark brown and black (dark
brown and black colors are due to partial alteration to birnessite).
Luster is vitreous to greasy to dull.
Diaphaneity is transparent to translucent or opaque for the
larger crystals.
Crystal System is hexagonal;
Crystal Habits include simple rhombohedra, aggregates of curved
rhombohedra forming druses, balls and rosettes; uncommonly found
as thin, twinned, triangular plates, scalenohedra, thin hexagonal
plates and botyroidal aggregates.
Cleavage {101} is perfect.
Fracture uneven to conchoidal.
Hardness is 3.5 to 4
Specific Gravity is approximately 3.7g/cm
Streak is white.
Associated Minerals include aegirine, albite, amphibole group, analcime,
ancylite, astrophyllite, bastnäsite, calcite, catapleiite, donnayite,
epididymite, eudialyte, fluorite, gaidonnayite, leifite, leucophanite,
mangan-neptunite, marcasite, microcline, monteregianite, natrolite,
nenadkevichite, nordstrandite, polylithionite, pyrochlore, pyrophanite,
sérandite, strontianite and zircon.
Distinguishing Features: Color, crystal habits.
Origin: Named in 1800 from the Greek rhodon, rose and chrosis
a coloring, referring to its color.

CLASSIFICATION:

Dana System
# 14.1.1.4

Strunz Classification
# V/B.02-50

REFERENCES:
MinRec 21:332-333 (1990), Dana 8:436-438 (1997)

DISTRIBUTION AND RARITY AT MONT SAINT-HILAIRE:

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