Emery is a granular, impure variety of corundum mixed with magnetite or hematite, often appearing as a dark, dense rock rather than a distinct crystal. It is prized primarily for its extreme hardness and abrasive properties, historically used for grinding wheels and sandpaper. Collectors typically find it in heavy, dark, massive chunks associated with metamorphic deposits.
Is this emery?
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 emery with a known reference. Emery sits at Mohs 8-9 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Emery leaves a none streak.
- 3Read the lusterHold the specimen under a strong light. Emery typically shows a dull luster.
- 4Match the color rangeCompare against the expected color range: dark gray, black, brownish-black.
- 5Look at form & habitCrystal system: trigonal. Typical habit: massive.
Often confused with
Emery vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Emery is noticeably harder (Mohs 8-9 vs. 5.5-6.5); streak differs — Emery leaves none, Magnetite leaves black; luster reads dull on Emery and metallic on Magnetite.
How to tell apart: Emery is noticeably harder (Mohs 8-9 vs. 5-6.5); streak differs — Emery leaves none, Iron Ore leaves reddish-brown to black; luster reads dull on Emery and metallic to submetallic on Iron Ore.
Often found alongside emery
Minerals reported to co-occur with emery. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Al₂O₃
- Mohs hardness
- 8-9
- Density
- 3.7-4.3 g/cm³
- Streak
- None
- Luster
- Dull
- Transparency
- Opaque
- Crystal system
- Trigonal
- Crystal habit
- Massive
- Cleavage
- None
- Rarity
- Common
- Uses
- Industrial, Abrasive, Polishing
- Host rock
- Metamorphic Rocks
- Typical price
- $5-20 for bulk samples
Where rockhounds find emery
2 mapped spotsClassic worldwide localities
- Greece
- Turkey
- USA
- Russia
- Italy
Field-hunting tip
Look in metamorphic rocks country — that is the host setting where emery typically forms. If you start seeing corundum, magnetite, hematite in float, you are in the right ground. Field specimens usually show a massive habit, so train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in Massachusetts, Montana — start trip planning there.
Common questions
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Find emery on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
