Protoenstatite is a high-temperature polymorph of magnesium silicate that is notably unstable at surface conditions. It is primarily identified in meteoritic samples or high-temperature synthetic experiments rather than typical terrestrial geological settings. Collectors usually find it represented in specialized petrological research collections or as minute inclusions within extraterrestrial matter.
Is this protoenstatite?
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 protoenstatite with a known reference. Protoenstatite sits at Mohs 5.5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Protoenstatite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Protoenstatite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: colorless, white, gray, greenish.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: rarely found as distinct crystals; typically identified via micro-inclusions or synthetic conditions.
Often confused with
Protoenstatite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside protoenstatite
Minerals reported to co-occur with protoenstatite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Mg₂Si₂O₆
- Mohs hardness
- 5.5
- Density
- 3.19 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Orthorhombic
- Crystal habit
- Rarely Found as Distinct Crystals; Typically Identified Via Micro-inclusions or Synthetic Conditions
- Cleavage
- Good
- Rarity
- Rare
- Uses
- Collector, Research
- Host rock
- Igneous
- Typical price
- $50-500 depending on specimen provenance and research quality
Where rockhounds find protoenstatite
Classic worldwide localities
- meteorites
- high-temperature volcanic environments
- synthetic laboratories
Field-hunting tip
Look in igneous country — that is the host setting where protoenstatite typically forms. If you start seeing olivine, diopside, plagioclase in float, you are in the right ground. Field specimens usually show a rarely found as distinct crystals; typically identified via micro-inclusions or synthetic conditions habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find protoenstatite on the map
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