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Spinel
Specimen | Catalog Number | Locality | Weight |
---|---|---|---|
Spinel | NMNH G11456 | Tanzania | 12.63 ct |
Pure spinel is colorless, but impurities give rise to a range of colors, most typically pink or red, but also purple, green and blue. Spinel is a magnesium aluminum oxide and forms when impure limestone is altered by heat and pressure. They are commonly found in occurrence with corundum (ruby and sapphire) and have historically been confused with each other due to their many similarities. Both minerals are hard, yield durable gems, and form in a range of colors. It was not until 1783 that spinel was recognized as a mineral distinct from corundum. The major sources of spinel gemstones are Burma, Sri Lanka, and Thailand. Other significant occurrences are Pakistan, Afghanistan, Tajikistan, Tanzania, Vietnam, and Russia. This 12.63ct spinel from Tanzania is exceptional for its purple color. The cushion cut gem is the first spinel from Tanzania in the National Gem Collection.