Search
Spinels
Dane A. Penland
Specimen | Catalog Number | Locality | Weight |
---|---|---|---|
Spinel | NMNH G2166 | Sri Lanka | 22.20 ct |
Spinel | NMNH G3685 | Myanmar [Burma] | 36.10 ct |
Spinel | NMNH G2165 | Sri Lanka | 29.70 ct |
Gift of Purchase in 1937.
It was not until 1783 that spinel was recognized as a mineral distinct from corundum (ruby and sapphire). Many of the world's most famous "rubies" are in fact red spinel. Spinel is magnesium aluminum oxide, and in its pure state, it is colorless. Chemical impurities give rise to a range of colors, most typically pink or red, purple, green, and blue. The 22.20-carat rosy pink spinel from Sri Lanka and the 36.10-carat red spinel from Burma owe their color to impurities of chromium. The purple-blue gem is from Sri Lanka and weighs 22.1ct. Natural spinel crystals, octahedral in shape, are also pictured in the photograph.