Magnesium aluminum oxide forming octahedral crystals. Red spinel was historically confused with ruby, including famous crown jewels. Color: Red, blue, green, black, pink. Luster: Vitreous. Streak: White. Cleavage: None conchoidal fracture. Hardness: 8. Transparency: Transparent to opaque. Crystal system: Isometric Cubic. Chemical formula: MgAl₂O₄. Specific gravity: 3.58-3.61. Formation: Forms in contact metamorphosed limestones and in aluminum-rich mafic igneous rocks. Common geological settings: Myanmar, Sri Lanka, Tanzania, Vietnam; found in marbles and as alluvial gems. Common look-alikes and related entries: Ruby, Garnet, Tourmaline.
These authoritative resources support category-level nomenclature, terminology, identification methods, and safety. When a specimen-specific safety warning appears, the public-health source listed here directly supports that precaution. They are not line-by-line citations for every other property on this entry, and natural specimens vary.
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GeoMiner
Last updated
2026-03-30T14:36:57.160708+00:00
Review status
Published; not independently peer-reviewed
IMA–CNMNC List of Mineral Names — International Mineralogical Association. Official mineral-name, nomenclature, and classification records.
Mineral ID Key — Mineralogical Society of America. Physical-property identification methods, repeat-testing guidance, and limitations.
Magnesium aluminum oxide forming octahedral crystals. Red spinel was historically confused with ruby, including famous crown jewels.
How can you identify Spinel?
Compare several properties rather than relying on colour alone. This entry records colour: Red, blue, green, black, pink; lustre: Vitreous; streak: White; Mohs hardness: 8; cleavage: None conchoidal fracture; crystal system: Isometric Cubic; transparency: Transparent to opaque. Confirm an important identification with additional field tests or qualified laboratory work.
How does Spinel form?
Forms in contact metamorphosed limestones and in aluminum-rich mafic igneous rocks.
Where is Spinel commonly found?
Myanmar, Sri Lanka, Tanzania, Vietnam; found in marbles and as alluvial gems.
What is Spinel commonly confused with?
Spinel may be confused with Ruby, Garnet, Tourmaline. Compare multiple diagnostic properties because colour and surface appearance can overlap.
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