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Eudidymite crystals - click for larger pic
Eudidymite twin
L. Horváth specimen
Photo by Violet Anderson
© Royal Ontario Museum

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

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

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Home > Mineral Descriptions > Eudidymite - (7 Photos)



Eudidymite
NaBeSi3O7(OH)

     Eudidymite is relatively rare at Mont Saint-Hilaire. It is the monoclinic dimorph of epididymite.

PHYSICAL CHARACTERISTICS:

Color is usually colorless to white, rarely pale pink.
Luster is vitreous to silky.
Diaphaneity is transparent to translucent.
Crystal System is monoclinic; C2/c.
Crystal Habits include thin tabular euhedral crystals, the twinned
   crystals sometimes form attractive stellate groups ressembling
   the epididymite trillings.
Cleavage {001} is perfect and {100} is distinct.
Fracture is uneven.
Hardness is 6 - 7.
Specific Gravity is approximately 2.55 g/cm3.
Streak is white.
Associated Minerals include aegirine, analcime, catapleiite,
   microcline, natrolite and rhodochrosite.
Distinguishing Features: Crystal habit (twinning).
Origin: Named in 1887 from the Greek eu, well, plus didymos, twin,
   alluding to its characteristic occurrence as twinned crystals.

CLASSIFICATION:

Dana System
# 66.3.1.3

Strunz Classification
# VIII/G.04-10

REFERENCES:
MinRec 21:309 (1990), Dana 8:1370-1371 (1997)

DISTRIBUTION AND RARITY AT MONT SAINT-HILAIRE:

MSH
¤¤¤

PE
¤¤

AP
¤¤

MX
--

SS
--

MC
--

HF
¤¤

BR
¤¤

SX
--

FR
--

Legend

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

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

Eudidymite crystals - click for larger pic
Eudidymite crystals
© Stephan Wolfsried

Eudidymite crystals - click for larger pic
Eudidymite crystals

© Doug Merson