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 7.5-8, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: white.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous, splendent to dull.
- 4Match the color rangeCompare against the expected color range: red, blue, green, pink, purple, black, colorless, brown.
- 5Look at form & habitCrystal system: cubic. Typical habit: euhedral crystals, massive.
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
- 7.5-8
- Density
- 3.6-4.1 g/cm³
- Streak
- White
- Luster
- Vitreous, splendent to dull
- Transparency
- Transparent to nearly opaque
- Crystal system
- Cubic
- Crystal habit
- Euhedral crystals, massive
- Cleavage
- Parting on {111}
- Fluorescence
- Red under SW and LW UV
- Rarity
- Common
- Uses
- Gemstone, Collector
- Host rock
- A common mineral, formed at high-temperatures as an accessory in igneous rocks, principally basalts, kimberlites, peridotites, and in xenoliths; in regionally metamorphosed aluminum-rich schists
Where rockhounds find spinel
7 mapped spotsClassic worldwide localities
- Franklin and Sterling Hill, Ogdensburg, Sussex Co., New Jersey, USA
- Midland, and at the Crestmore quarry, Riverside Co., California, USA
- Mogok, Myanmar (Burma) and in Sri Lanka, in the Ratnapura and Elahera districts
- Burgess, Ontario, and Wakefield, Quebec, Canada
- Eifel district, and at Bodenmais, Bavaria, Germany
- Monte Somma and Vesuvius, Campania, Italy
Field-hunting tip
Where it forms: A common mineral, formed at high-temperatures as an accessory in igneous rocks, principally basalts, kimberlites, peridotites, and in xenoliths; in regionally metamorphosed aluminum-rich schists. If you start seeing forsterite, chondrodite, scapolite in float, you are in the right ground. Typical habit: euhedral crystals, massive. Train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in Utah, New York, New Jersey. Start trip planning there.
More spinel photos
Common questions
How do you identify spinel?+
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Find spinel on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
