mineral
Black Spinel
Magnesium Aluminum Oxide (MgAl2O4)
AI-generated identification · may be incorrectHardness: 8.0 on Mohs scale; Color: Jet black, opaque; Luster: Vitreous (glassy) to sub-metallic; Crystal structure: Isometric (cubic); Cleavage: Indistinct; Specific Gravity: 3.54 - 3.63
- Hardness
- 8
- Color
- Jet black, opaque
- Luster
- Vitreous (glassy) to sub-metallic
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Physical properties
Hardness: 8.0 on Mohs scale; Color: Jet black, opaque; Luster: Vitreous (glassy) to sub-metallic; Crystal structure: Isometric (cubic); Cleavage: Indistinct; Specific Gravity: 3.54 - 3.63
Formation & geological history
Formed through regional or contact metamorphism of limestone and dolostones. Often found in magnesium-rich igneous rocks and as water-worn pebbles in alluvial deposits. Age varies by deposit but found in Precambrian to Cenozoic formations.
Uses & applications
Primarily used as a gemstone in high-end and fashion jewelry due to its high hardness and brilliant luster. Often used as an affordable alternative to black diamond or black sapphire.
Geological facts
Black spinel is often referred to as 'the great imposter' because it was historically mistaken for other stones. It is one of the few natural gemstones that occurs in a true black color without treatment.
Field identification & locations
Identify in the field by its high hardness (it will scratch glass and quartz) and lack of magnetism compared to magnetite. Commonly located in Sri Lanka, Thailand, Cambodia, and Myanmar. For collectors, look for its characteristic octahedral crystal shape.
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Other mineral specimens
Gneiss or Schist
Gneiss or Mica Schist with Garnet
Metamorphic
Sandstone (with potential mineral staining/concretions)
Arenite (SiO2 based)
sedimentary
Tumbled granite
Granite, a coarse-grained felsic intrusive igneous rock
igneous
Epidote
Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)
metamorphic
Pegmatite with Tourmaline and Quartz
Igneous Pegmatite
igneous
Granite
Granite (Phaneritic intrusive igneous rock)
igneous