Black spinel is the iron rich and opaque variety of spinel. It has also been called pleonaste and ceylonite. Local Thai miners call it “nin” or black stone. Stones are free of fractures and displays a high luster. High-quality black spinel is known is known to come from Mexico and Thailand. Most material comes from the Bo Phloi District of Kanchanaburi Province, Thailand where it is was a byproduct of blue sapphire mining. When the blue sapphire ran out in the early 2000’s the local cutters started faceting the black spinel.
Black Spinel Classification
||Black Spinel |
Black Spinel Characteristic Physical properties
Gahnospinel is the rare violetish to dark blue, zinc-rich variety of spinel. A variety of spinel rich in zinc, much of the world's supply of gahnospinel comes from Sri Lanka. Since gahnospinel is chemically midway between spinel and gahnite, hence its name is a combination of the two. The first half is in honor of Johann Gottlieb Gahn, a Swedish chemist and mineralogist.
Gahnospinel Optical Properties
||SWUV: Inert |
Gahnospinel Characteristic Physical properties
Ranging from dark green to black in color, gahnite is a rare member of the spinel group. It was first discovered in Sweden 1807 and named in honor of Swedish chemist J.G. Gahn, who is credited with the discovery of manganese. While highly prized by mineral collectors for its octahedral crystal formation, gahnite is on occasion cut into faceted gems.
Gahnite Optical Properties
Gahnite Characteristic Physical properties
Natural cobalt spinel is vivid blue and is colored by cobalt, The color ranges from greenish blue to violet blue. Natural cobalt spinel can be separated from lab created blue spinel by its RI and spectra.
Cobalt Spinel Classification
||Cobalt Spinel |
Cobalt Spinel Optical Properties
||Weak orange red |
Cobalt Spinel Characteristic Physical properties
||Fingerprints or octahedra stringers, iron stained fractures |