Breyite is a rare high-pressure polymorph of calcium silicate found as inclusions within diamonds originating from the Earth's lower mantle. Because it only forms under extreme deep-earth conditions, it is almost exclusively identified through microscopic analysis of diamond-hosted grains.
Is this breyite?
4-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 breyite with a known reference. Breyite sits at Mohs 7-7.5, softer than the next harder reference, harder than the previous one.
- 2Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 3Match the color rangeCompare against the expected color range: colorless.
- 4Look at form & habitCrystal system: triclinic. Typical habit: microscopic inclusions.
Often confused with
Breyite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside breyite
Minerals reported to co-occur with breyite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CaSiO₃
- Mohs hardness
- 7-7.5
- Density
- 3.072 g/cm³
- Colors
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Triclinic
- Crystal habit
- Microscopic inclusions
- Cleavage
- None observed
- Rarity
- Rare
- Uses
- Collector, Scientific research
- Host rock
- The second most abundant mineral inclusion after ferropericlase in diamonds of super-deep origin; only found in super-deep diamonds
Where rockhounds find breyite
Classic worldwide localities
- Sao Luiz diamond placers, Juina area, Mato Grosso State, Brazil
Field-hunting tip
Where it forms: The second most abundant mineral inclusion after ferropericlase in diamonds of super-deep origin; only found in super-deep diamonds. If you start seeing diamond, ferropericlase, ringwoodite in float, you are in the right ground. Typical habit: microscopic inclusions. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify breyite?+
Where is breyite found?+
What rocks look like breyite?+
What minerals are found with breyite?+
What kind of rock does breyite form in?+
What is breyite used for?+
Find breyite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
