Lonsdaleite is a rare hexagonal polymorph of carbon typically found at meteorite impact sites where high pressures transform graphite. It is almost exclusively found in microscopic quantities, making high-quality collector specimens extremely rare and valuable to scientific researchers.
Is this lonsdaleite?
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 lonsdaleite with a known reference. Lonsdaleite sits at Mohs 3, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: brownish yellow.
- 3Read the lusterHold the specimen under a strong light. Luster: adamantine.
- 4Match the color rangeCompare against the expected color range: brownish black, light brownish yellow.
- 5Look at form & habitCrystal system: hexagonal. Typical habit: microscopic crystals.
Often confused with
Lonsdaleite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Diamond is the harder of the two (Mohs 10 vs. 3); streak differs, so Lonsdaleite leaves brownish yellow, Diamond leaves colorless.
How to tell apart: Lonsdaleite is noticeably harder (Mohs 3 vs. 1-2); streak differs, so Lonsdaleite leaves brownish yellow, Graphite leaves black to steel-gray, shining; luster reads adamantine on Lonsdaleite and metallic; may be dull, earthy on Graphite.
Often found alongside lonsdaleite
Minerals reported to co-occur with lonsdaleite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- C
- Mohs hardness
- 3
- Density
- 3.3-3.52 g/cm³
- Colors
- Brownish blackLight brownish yellow
- Streak
- Brownish yellow
- Luster
- Adamantine
- Transparency
- Transparent
- Crystal system
- Hexagonal
- Crystal habit
- Microscopic crystals
- Cleavage
- Perfect
- Rarity
- Rare
- Uses
- Collector, Scientific research
- Host rock
- Discovered in the residue (ca. 200 mg) from the dissolution of 5 kg of Cañon Diablo meteorite
Where rockhounds find lonsdaleite
Classic worldwide localities
- Found in soil at the Tunguska explosion site, Federated SSR, Russia
- Nördlinger Ries Crater, Bavaria, Germany
- Sudbury impact structure, Ontario, Canada
Field-hunting tip
Where it forms: Discovered in the residue (ca. 200 mg) from the dissolution of 5 kg of Cañon Diablo meteorite. If you start seeing schreibersite, cohenite, taenite in float, you are in the right ground. Typical habit: microscopic crystals. Train your eye for that shape before scanning the outcrop.
Common questions
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Find lonsdaleite on the map
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