Alwilkinsite-(Y) is an exceptionally rare secondary uranium mineral typically found as small, delicate, yellow acicular crystals or efflorescent crusts. It forms in the oxidized zones of uranium-bearing pegmatites, often occurring as a late-stage alteration product.
Is this alwilkinsite-(y)?
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 alwilkinsite-(y) with a known reference. Alwilkinsite-(Y) sits at Mohs 2 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Alwilkinsite-(Y) leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Alwilkinsite-(Y) typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: yellow, greenish-yellow.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: acicular crystals, efflorescent crusts.
Often confused with
Alwilkinsite-(Y) vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Alwilkinsite-(Y) leaves white, Johannite leaves pale green.
How to tell apart: Streak differs — Alwilkinsite-(Y) leaves white, Zippeite leaves yellow; luster reads vitreous on Alwilkinsite-(Y) and pearly on Zippeite.
Often found alongside alwilkinsite-(y)
Minerals reported to co-occur with alwilkinsite-(y). Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Y(UO₂)₃(SO₄)₂(OH)₇·7H₂O
- Mohs hardness
- 2
- Density
- 2.8 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Acicular Crystals, Efflorescent Crusts
- Cleavage
- Perfect
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Granite Pegmatite
- Typical price
- $50-300 per specimen
Where rockhounds find alwilkinsite-(y)
Classic worldwide localities
- Harding Mine, New Mexico, USA
Field-hunting tip
Look in granite pegmatite country — that is the host setting where alwilkinsite-(y) typically forms. If you start seeing uraninite, vandendriesscheite, kasolite in float, you are in the right ground. Field specimens usually show a acicular crystals, efflorescent crusts habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find alwilkinsite-(y) on the map
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