Spinel (MgAl₂O₄) is the parent species of the spinel oxide group and a cherished gem mineral for centuries. Famous historical “rubies” turned out to be red spinels — including the “Black Prince’s Ruby” in the British Crown Jewels and Russia’s “Tamerlane Ruby.” Modern gem spinels come from Mogok (Myanmar) and Mahenge (Tanzania), with bright red, pink, and cobalt-blue varieties.
Key Facts
- Mohs hardness 7.5–8.
- Isometric; classic octahedral crystals — “spinel-twin” reentrant twinning is diagnostic.
- Color from trace metal substitution: Cr (red), Co (blue), Fe (black, magnetite var.).
- Parent of spinel-group oxides (magnetite, chromite, gahnite, etc.).
- Historically confused with ruby until 18th-century chemistry distinguished them.
Notable Localities
Mogok (Myanmar) and Mahenge (Tanzania) supply gem material. Ratnapura (Sri Lanka) yields alluvial gem crystals. Vietnam (Luc Yen) supplies modern collector pieces.
Found at these Localities
- Labrador Coast (Tabor Island, Nain) (拉布拉多海岸(拉长石产地))
- Mogok Stone Tract (抹谷宝石产地)
