Epididymite

NaBeSi(OH)

Mont Saint-Hilaire hosts superb trillings of epididymite to 1cm. It is fairly abundant at the site in pegmatites and comes in a variety of habits.

PHYSICAL CHARACTERISTICS:

Color is usually colorless for singles and white for twins.
Luster is vitreous to silky.
Diaphaneity is transparent for single crystals and translucent
to opaque on twins.
Crystal System is orthorhombic; Pnam
Crystal Habits include fibrous to acicular, bladed long prismatic to
blocky and equant prisms; twins of acicular to prismatic crystals
forming attractive spherical and barrel-shaped aggregates. Superb
trilling forming tabular or columnar peudohexagonal crystals to 1cm.
Cleavage {001} is perfect and {100} is distinct.
Fracture is uneven to splintery.
Hardness is 6 – 7.
Specific Gravity is approximately 2.58 g/cm
Streak is white.
Associated Minerals include aegirine, albite, amphibole group,
analcime, ancylite, astrophyllite, behoite, calcite, catapleiite, chlorite
group, elpidite, eudialyte, fluorite, gaidonnayite, genthelvite,
leucophanite, molybdenite, natrolite, nenadkevichite, pyrite,
pyrochlore, pyrophanite, rhodochrosite, rutile, sérandite, siderite,
sphalerite, steacyite and yofortierite.
Distinguishing Features: Crystal habit, luster and twinning.
Origin: Named in 1893 from the Greek epi, near and didymos, twin,
for its dimorphous relationship with eudidymite.

CLASSIFICATION:

Dana System
# 66.3.1.4

Strunz Classification
# VIII/G.04-20

REFERENCES:
MinRec 21:307-308 (1990), Dana 8:1371 (1997)

DISTRIBUTION AND RARITY AT MONT SAINT-HILAIRE:

MSH
¤¤¤

Legend

Epididymite crystals - click for larger pic
Epididymite crystals
© Doug Merson

Epididymite crystals - click for larger pic
Epididymite crystals
© Doug Merson

Epididymite crystals - click for larger pic
Epididymite crystals
© Modris Baum

Epididymite crystals - click for larger pic
Epididymite crystals
Photo by R. Lavinsky
© www.irocks.com

Epididymite crystals - click for larger pic
Epididymite crystals
© Gilles Haineault

Epididymite sixling - click for larger pic
Epididymite sixling
© Modris Baum

Epididymite crystals - click for larger pic
Epididymite crystals
Photo by R. Lavinsky
© www.irocks.com

Epididymite crystals - click for larger pic
Epididymite crystals
© Gilles Haineault