Photo by Violet Anderson
© Royal Ontario Museum
© Doug Merson
© Modris Baum
© Gilles Haineault
Genthelvite is rare at Mont Saint-Hilaire. Some crystals to 5cm have been found, the largest known for the species. Genthelvite fluoresces intense green under SW and LW; and retains strong phosphorescence for short periods.
Color is usually colorless, white or pale yellow on smaller crystals
and white, pale to lemon-yellow, greenish yellow, very pale green
and pale brown on the larger crystals.
Luster is vitreous, resinous or greasy on broken surfaces.
Diaphaneity: transparent to translucent on smaller crystals and
generally opaque on larger crystals.
Crystal System is isometric; 43
Crystal Habits include sharp simple tetrahedra often with minor
modifications, randomly disseminated grains or small embedded
Cleavage none observed.
Fracture is conchoidal to uneven.
Hardness is 6.
Specific Gravity is approximately 3.6 g/cm
Streak is white.
Associated Minerals include aegirine, albite, analcime, ancylite,
astrophyllite, calcite, catapleiite, fluorite, gonnardite, leifite,
microcline, polylithionite, pyrochlore, rhodochrosite, sérandite and
Distinguishing Features: Crystal habit.
Origin: Named in 1944 after Frederick August Ludwig Karl William
Genth (1820-1893), Professor of Chemistry, University of
Pennsylvania, and to recognize its similarity to helvite.
MinRec 21:311-312 (1990), Dana 8:1631 (1997)
DISTRIBUTION AND RARITY AT MONT SAINT-HILAIRE:
© Modris Baum
© Quintin Wight
Genthelvite crystals under SW
Photo by R. Lavinsky