Rhodolite

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Rhodolite
Category	Varietal name
Chemical formula	(Mg,Fe)3Al2(SiO4)3 [1]
Identification
Color	light to dark purplish red through reddish purple
Crystal system	cubic [1]
Cleavage	none, may show indistinct parting [1]
Fracture	conchoidal [1]
Mohs Scale hardness	7 - 7.5 [1]
Luster	greasy to vitreous [1]
Polish luster	vitreous [1]
Refractive index	1.760 (+.010, -.020) [1]
Optical Properties	Single refractive, often anomalous double refractive [1]
Birefringence	none [1]
Dispersion	.026 [1]
Pleochroism	none [1]
Ultraviolet fluorescence	inert [1]
Absorption spectra	usually at 504, 520, and 573nm, may also have faint lines at 423, 460, 610 and 680-690nm [1]
Specific gravity	3.84 (+/- .10) [1]

Rhodolite is a varietal name for rose-pink to red mineral pyrope, a species in the garnet group. It is found in Cowee Valley, Macon County, North Carolina. The name is derived from the Greek for "rose-like", in common with many pink mineral types (e.g. rhodochrosite, rhodonite), but rhodolite itself is not officially recognised as a mineralogical term. This colouration, and the commonly inclusion-free nature of garnet from this locality, has led to rhodolite being used as a semi-precious gemstone. Chemically, rhodolite is an iron-magnesium-aluminium silicate, part of the pyrope-almandine solid-solution series, with an approximate garnet composition of Py₇₀Al₃₀.

[edit] References

1. ^ ^{a b c d e f g h i j k l m n o} (Gia), Gemological. Gem Reference Guide. City: Gemological Institute of America (GIA), 1988. ISBN 0-87311-019-6

• mindat.org: Rhodolite