Edgrewite is an extremely rare calcium silicate member of the humite group found in skarn zones. It typically occurs as small, indistinct grains within limestone contact metamorphic environments, often requiring X-ray diffraction for definitive identification.
Is this edgrewite?
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 edgrewite with a known reference. Edgrewite sits at Mohs 6, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Edgrewite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Edgrewite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: colorless, white, gray.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: granular, anhedral crystals.
Often confused with
Edgrewite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside edgrewite
Minerals reported to co-occur with edgrewite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Ca₉Si₄O₁₆F₂
- Mohs hardness
- 6
- Density
- 3.17 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Granular, Anhedral Crystals
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Skarn Deposits Formed By Contact Metamorphism
- Typical price
- Not publicly traded; mostly of research interest.
Where rockhounds find edgrewite
Classic worldwide localities
- Kizil-Kaya, Alai Range, Kyrgyzstan
- Aktyuz ore field, Kyrgyzstan
Field-hunting tip
Look in skarn deposits formed by contact metamorphism country, the host setting where edgrewite typically forms. If you start seeing calcite, wollastonite, diopside in float, you are in the right ground. Field specimens usually show a granular, anhedral crystals habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find edgrewite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
