Nambulite Value, Price, and Jewelry Information

Rob Lavinsky, iRocks.com – CC-BY-SA-3.0 [CC-BY-SA-3.0], via Wikimedia Commons

Nambulite

The color of Namibian nambulite is a striking orange-red, very intense, and not really like any other gem I have seen. Cut stones would be both extremely rare and quite magnificent, perhaps bearing some similarities to rhodonite.

Nambulite Information

Data Value
Name Nambulite
Colors Reddish brown, orange-brown, orange.
Crystallography Triclinic. Crystals prismatic, flattened, and wedge shaped.
Refractive Index 1.707-1.730
Luster Vitreous.
Hardness 6.5
Specific Gravity 3.51
Birefringence 0.023
Cleavage Perfect 1 direction, distinct 1 direction
Dispersion Weak.
Stone Sizes Gems up to about 10 carats could potentially be cut from Namibian crystals.
Luminescence No data.
Luminescence Present No
Transparency Transparent.
Absorption Spectrum Not diagnostic.
Formula

NaLiMn8Si10O28(OH)2

Pleochroism

Weak.

Optics

a = 1.707; β = 1.710; γ = 1.730. Biaxial (+), 2V= 30°.

Optic Sign Biaxial +

Optics: a = 1.707; β=1.710; γ=1.730.

Biaxial (+), 2V= 30°.

Occurrence: Nambulite is a rare mineral reported in crystals up to 8 mm long at the Tunakozawa Mine, Northeast Japan. These crystals are found in veins cutting manganese oxide ores. Much larger crystals, up to approximately 3 cm across, have more recently been found in Namibia, at the Kombat Mine, near Tsumeb. I have seen a completely transparent crystal in a private collection that would yield about 20-25 carats of flawless faceted gems, the largest of these perhaps 10 carats in weight.

Comments: The color of Namibian nambulite is a striking orange-red, very intense, and not really like any other gem I have seen. Cut stones would be both extremely rare and quite magnificent, perhaps bearing some similarities to rhodonite.

Name: After Professor Matsuo Nambu of Tohoku University, Japan, for his studies of manganese minerals.