Clinohedrite is a prized fluorescent mineral best known from the Franklin-Sterling Hill mining district. It typically forms prismatic crystals or radial sprays that exhibit a characteristic, vivid orange fluorescence under shortwave ultraviolet light.
Is this clinohedrite?
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 clinohedrite with a known reference. Clinohedrite 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. Streak: white.
- 3Read the lusterHold the specimen under a strong light. Luster: brilliant, glassy; pearly on {010}.
- 4Match the color rangeCompare against the expected color range: colorless, white, amethystine red.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: prismatic crystals, radial aggregates, massive.
Often confused with
Clinohedrite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Luster reads brilliant, glassy; pearly on {010} on Clinohedrite and vitreous, subpearly, adamantine, rarely silky on Hemimorphite.
How to tell apart: Luster reads brilliant, glassy; pearly on {010} on Clinohedrite and vitreous to resinous on Willemite.
Often found alongside clinohedrite
Minerals reported to co-occur with clinohedrite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CaZn(SiO₄)·H₂O
- Mohs hardness
- 5.5
- Density
- 3.28-3.335 g/cm³
- Streak
- White
- Luster
- Brilliant, glassy; pearly on {010}
- Transparency
- Transparent to translucent
- Crystal system
- Monoclinic
- Crystal habit
- Prismatic crystals, radial aggregates, massive
- Cleavage
- Perfect on {010}
- Fluorescence
- Orange under SW and LW UV
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In a metamorphosed stratiform zinc orebody (Franklin, New Jersey, USA)
Where rockhounds find clinohedrite
Classic worldwide localities
- Franklin, Sussex Co., New Jersey, USA
- Christmas mine, Gila Co., Arizona, USA
Field-hunting tip
Where it forms: In a metamorphosed stratiform zinc orebody (Franklin, New Jersey, USA). If you start seeing hancockite, nasonite, glaucochroite in float, you are in the right ground. Typical habit: prismatic crystals, radial aggregates, massive. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify clinohedrite?+
Where is clinohedrite found?+
Is clinohedrite safe to handle?+
What rocks look like clinohedrite?+
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Find clinohedrite on the map
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