Spinel is a durable and highly sought-after mineral that often forms sharp, well-defined octahedral crystals. While it is famous for its historical confusion with ruby, collectors prize it for its diverse color palette and high luster. It is most commonly found in contact metamorphic marbles and associated alluvial deposits.
Is this spinel?
5-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Test the hardnessTry to scratch spinel with a known reference. Spinel sits at Mohs 8 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Spinel leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Spinel typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: red, blue, green, pink, purple, black, colorless.
- 5Look at form & habitCrystal system: cubic. Typical habit: octahedral crystals, often twinned.
Often confused with
Spinel vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside spinel
Minerals reported to co-occur with spinel. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- MgAl₂O₄
- Mohs hardness
- 8
- Density
- 3.5-4.1 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Cubic
- Crystal habit
- Octahedral Crystals, Often Twinned
- Cleavage
- Indistinct
- Fluorescence
- Red Varieties Often Fluoresce Red Under LW UV
- Rarity
- Common
- Uses
- Gemstone, Collector
- Host rock
- Metamorphosed Limestones and Marbles, Alluvial Gravels
- Typical price
- $20-200 per gram for mineral specimens, significant premium for high-quality gemstones
Where rockhounds find spinel
5 mapped spotsClassic worldwide localities
- Myanmar
- Sri Lanka
- Tajikistan
- Vietnam
- Afghanistan
- Tanzania
Field-hunting tip
Look in metamorphosed limestones and marbles, alluvial gravels country — that is the host setting where spinel typically forms. If you start seeing corundum, calcite, phlogopite in float, you are in the right ground. Field specimens usually show a octahedral crystals, often twinned habit, so train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in Utah, New Jersey, North Carolina — start trip planning there.
Common questions
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Find spinel on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
