Gadolinite Value, Price, and Jewelry Information

Gadolinite

This is not a terribly attractive gemstone, but faceted gems would be a tremendous rarity. The material is quite brittle, but there is no cleavage to cause problems in cutting. I do not know of the existence of a faceted gem at this writing.

Gadolinite Information

Data Value
Name Gadolinite
Colors Black, greenish black, brown, very rarely light green.
Crystallography Monoclinic. Crystals rough and coarse often terminated; massive.
Refractive Index 1.77-1.82
Luster Vitreous to greasy.
Hardness 6.5 - 7.0
Fracture Conchoidal
Specific Gravity 4.0-4.65 (usually 4.4); metamict material 4.2.
Birefringence High, and variable 0.01-0.04.
Cleavage None
Stone Sizes Norwegian crystals have been found up to 4 inches across and nodules up to 60 pounds have been unearthed in Texas. This massive material cuts cabochons up to several pounds. Faceted gems, however, would be very tiny and very rare since the mineral is rarely transparent, even in thin splinters.
Transparency Opaque. Very rarely transparent, even in thin splinters.
Formula

Be2FeY2Si2O10

Optics

a = 1.77-1.78; γ = 1.78-1.82. Biaxial ( + ), 2V = 85°. Usually metamict and amorphous, hence isotropic.

Optic Sign Biaxial +

Streak: Greenish gray.

Optics:  a = 1.77-1.78; γ= 1.78-1.82.

Biaxial ( + ), 2V = 85°. Usually metamict and amorphous, hence isotropic.

Occurrence: Granites and granite pegmatites. Colorado; Texas; Arizona.

Greenland; Sweden; Norway; USSR; Japan; Switzerland; Australia.

Comments: This is not a terribly attractive gemstone, but faceted gems would be a tremendous rarity. The material is quite brittle, but there is no cleavage to cause problems in cutting. I do not know of the existence of a faceted gem at this writing.

Name: After the Swedish chemist, J. Gadolin.