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 3.5-4 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Keilite leaves a brownish-black streak.
- 3Read the lusterHold the specimen under a strong light. Keilite typically shows a submetallic luster.
- 4Match the color rangeCompare against the expected color range: black, brown.
- 5Look at form & habitCrystal system: cubic. Typical habit: massive, anhedral grains.
Often confused with
Keilite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Keilite leaves brownish-black, Troilite leaves black; luster reads submetallic on Keilite and metallic on Troilite.
How to tell apart: Streak differs — Keilite leaves brownish-black, Alabandite leaves dark green to olive-green; luster reads submetallic on Keilite and submetallic to dull on Alabandite.
How to tell apart: Streak differs — Keilite leaves brownish-black, Sphalerite leaves white to yellow-brown; luster reads submetallic on Keilite and resinous to submetallic 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
- (Fe,Mg)S
- Mohs hardness
- 3.5-4
- Density
- 4.5-4.8 g/cm³
- Streak
- Brownish-black
- Luster
- Submetallic
- Transparency
- Opaque
- Crystal system
- Cubic
- Crystal habit
- Massive, Anhedral Grains
- Cleavage
- None Observed
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Enstatite Chondrite Meteorites
- Typical price
- $100-500+ per specimen
Where rockhounds find keilite
Classic worldwide localities
- Kainsaz meteorite
- Efremovka meteorite
- Indarch meteorite
Field-hunting tip
Look in enstatite chondrite meteorites country — that is the host setting where keilite typically forms. If you start seeing troilite, kamacite, enstatite in float, you are in the right ground. Field specimens usually show a massive, anhedral grains habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find keilite on the map
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