Keilite is a rare iron-magnesium sulfide mineral primarily found in extraterrestrial settings like enstatite chondrite meteorites. It typically occurs as anhedral grains within the matrix of these meteorites and is visually indistinguishable from other iron sulfides without microscopic analysis or chemical testing.
Is this keilite?
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 keilite with a known reference. Keilite sits at Mohs ~4, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: brownish-black.
- 3Read the lusterHold the specimen under a strong light. Luster: metallic.
- 4Match the color rangeCompare against the expected color range: gray.
- 5Look at form & habitCrystal system: cubic. Typical habit: microscopic crystals.
Often confused with
Keilite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Keilite leaves brownish-black, Troilite leaves dark grayish brown.
How to tell apart: Streak differs, so Keilite leaves brownish-black, Alabandite leaves dark green; luster reads metallic on Keilite and submetallic on Alabandite.
How to tell apart: Streak differs, so Keilite leaves brownish-black, Sphalerite leaves pale brown to pale yellow and white; luster reads metallic on Keilite and resinous to adamantine on Sphalerite.
Often found alongside keilite
Minerals reported to co-occur with keilite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- FeS
- Mohs hardness
- ~4
- Density
- 3.59-3.958 g/cm³
- Colors
- Streak
- Brownish-black
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Cubic
- Crystal habit
- Microscopic crystals
- Cleavage
- Good on (001), (010), and (100)
- Rarity
- Rare
- Uses
- Collector
- Host rock
- An accessory mineral in enstatite chondrite and achondrite meteorites
Where rockhounds find keilite
Classic worldwide localities
- Abee (type locality), Adhi-Kot, Saint-Sauveur, LEW 88180, RKP A80259, LEW 87119, LEW 88714, Y-791790, Y-791811, Y-86760, and Y8404 chondrite meteorites
Field-hunting tip
Where it forms: An accessory mineral in enstatite chondrite and achondrite meteorites. If you start seeing niningerite, enstatite, kamacite in float, you are in the right ground. Typical habit: microscopic crystals. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify keilite?+
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What rocks look like keilite?+
What minerals are found with keilite?+
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Find keilite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
