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?
2-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.
- 2Look 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
- 3.30 g/cm³
- Transparency
- Translucent to transparent
- Crystal system
- Orthorhombic
- Crystal habit
- Rarely found as distinct crystals; typically identified via micro-inclusions or synthetic conditions
- Rarity
- Rare
- Uses
- Collector, Research
- Host rock
- As nano-inclusions in gem-quality “watermelon” labradorite “sunstones” (Oregon)
Where rockhounds find protoenstatite
Classic worldwide localities
- Meteorites
- High-temperature volcanic environments
- Synthetic laboratories
Field-hunting tip
Where it forms: As nano-inclusions in gem-quality “watermelon” labradorite “sunstones” (Oregon). If you start seeing labradorite plagioclase, copper, clinoenstatite in float, you are in the right ground. Typical habit: rarely found as distinct crystals; typically identified via micro-inclusions or synthetic conditions. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify protoenstatite?+
Where is protoenstatite found?+
What rocks look like protoenstatite?+
What minerals are found with protoenstatite?+
What kind of rock does protoenstatite form in?+
What is protoenstatite used for?+
Find protoenstatite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
