Grandidierite Value, Price, and Jewelry Information


GRANDIDIERITE: Madagascar (1.1). Photo © Joel E. Arem, PhD, FGA. Used with permission.

Grandidierite is a rather rare mineral, with a lovely blue-green color. It is never transparent enough to facet, but attractive, sometimes even jadelike cabochons are cuttable from the translucent material. The high hardness makes it suitable for wear, although cutters have to pay close attention to the cleavage. Cut grandidierite is seldom seen in collections because few collectors have even heard of it or know it exists in cuttable form.

Grandidierite Value

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Grandidierite Information

DataValue
NameGrandidierite
Crystallography Orthorhombic. Crystals elongated and not well formed; massive.
Colors Blue-green; translucent.
Luster Vitreous
Hardness 7.5
Specific Gravity 2.85-3.0
Birefringence 0.039
Cleavage Perfect 1 direction, good 1 direction.
Stone SizesCut as cabochons up to about 1 inch (1-10 carats). At best, the material is translucent, and generally is opaque.
Luminescence None.
Spectral Not diagnostic.
Formula(Mg,Fe)Al3BSiO9.
Pleochroism Strong: dark blue-green/colorless/ dark green.

Optics: a = 1.583-1.602;  β=1.618-1.636; γ=1.622-1.639.

Biaxial (-), 2V= 30°.

(Madagascar stone: a = 1.583;  γ= 1.622; S.G. = 2.85).

Occurrence: Generally in pegmatites.

Andrahomana, South Madagascar: only well-known locality.

Comments: Grandidierite is a rather rare mineral, with a lovely blue-green color. It is never transparent enough to facet, but attractive, sometimes even jadelike cabochons are cuttable from the translucent material. The high hardness makes it suitable for wear, although cutters have to pay close attention to the cleavage. Cut grandidierite is seldom seen in collections because few collectors have even heard of it or know it exists in cuttable form.

Name: After Alfred Grandidier, a French explorer, who described the natural history and geography of Madagascar.