Haynesite is a rare uranyl selenite mineral typically found as delicate, pale yellow acicular crystal sprays or coatings. It is primarily known from oxidized portions of uranium-bearing deposits, often forming in association with other rare secondary minerals.
Is this haynesite?
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 haynesite with a known reference. Haynesite sits at Mohs 2-3 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Haynesite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Haynesite typically shows a pearly luster.
- 4Match the color rangeCompare against the expected color range: pale yellow, golden yellow.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: acicular crystals, radial aggregates, crusts.
Often confused with
Haynesite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Haynesite leaves white, Cuprosklodowskite leaves pale green; luster reads pearly on Haynesite and vitreous on Cuprosklodowskite.
How to tell apart: Streak differs — Haynesite leaves white, Autunite leaves pale yellow.
Often found alongside haynesite
Minerals reported to co-occur with haynesite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (UO₂)₃(SeO₃)₂O(OH)₂·5H₂O
- Mohs hardness
- 2-3
- Density
- 4.2 g/cm³
- Colors
- Streak
- White
- Luster
- Pearly
- Transparency
- Translucent
- Crystal system
- Orthorhombic
- Crystal habit
- Acicular Crystals, Radial Aggregates, Crusts
- Cleavage
- Perfect On {010}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Oxidized Hydrothermal Uranium-selenium Deposits
- Typical price
- $50-300 per specimen
Where rockhounds find haynesite
Classic worldwide localities
- Repete mine, Utah, USA
Field-hunting tip
Look in oxidized hydrothermal uranium-selenium deposits country — that is the host setting where haynesite typically forms. If you start seeing calcite, gypsum, quartz in float, you are in the right ground. Field specimens usually show a acicular crystals, radial aggregates, crusts habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find haynesite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
