Chayesite is a rare member of the milarite group, typically occurring as small, deep blue prismatic crystals. It is most prominently found within alkaline igneous complexes such as those on the Kola Peninsula, where it forms in association with sodium-rich minerals.
Is this chayesite?
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 chayesite with a known reference. Chayesite sits at Mohs 5-6, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: white.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: dark blue.
- 5Look at form & habitCrystal system: hexagonal. Typical habit: prismatic crystals.
Often confused with
Chayesite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside chayesite
Minerals reported to co-occur with chayesite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- KMg₄Fe[Si₁₂O₃₀]
- Mohs hardness
- 5-6
- Density
- 2.68 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Hexagonal
- Crystal habit
- Prismatic crystals
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A late-crystallizing mineral, nonuniformly distributed in the groundmass of lamproites
Where rockhounds find chayesite
Classic worldwide localities
- Moon Canyon, east of Francis, Summit Co., Utah, USA
- Cancarix, Albacete Province, Spain
Field-hunting tip
Where it forms: A late-crystallizing mineral, nonuniformly distributed in the groundmass of lamproites. If you start seeing potassian richterite, diopside, potassic feldspar in float, you are in the right ground. Typical habit: prismatic crystals. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify chayesite?+
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What rocks look like chayesite?+
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Find chayesite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
