Seelite is a rare magnesium-uranium arsenate mineral known for its vibrant yellow, micaceous platy crystals. It is typically found as a secondary mineral in uranium-rich ore deposits, often forming thin crusts or small crystal sprays on matrix.
Is this seelite?
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 seelite with a known reference. Seelite 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. Seelite leaves a yellow streak.
- 3Read the lusterHold the specimen under a strong light. Seelite typically shows a pearly luster.
- 4Match the color rangeCompare against the expected color range: yellow, lemon yellow.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: platy crystals, crusts.
Often confused with
Seelite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Seelite leaves yellow, Autunite leaves pale yellow.
How to tell apart: Streak differs — Seelite leaves yellow, Torbernite leaves pale green; luster reads pearly on Seelite and vitreous on Torbernite.
Often found alongside seelite
Minerals reported to co-occur with seelite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Mg₃(UO₂)₂(AsO₄)₂·10H₂O
- Mohs hardness
- 2-3
- Density
- 3.85 g/cm³
- Colors
- Streak
- Yellow
- Luster
- Pearly
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Platy Crystals, Crusts
- Cleavage
- Perfect
- Fluorescence
- Bright Yellow Under SW UV
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Hydrothermal Uranium-bearing Veins
- Typical price
- $50-300 per specimen depending on size and intensity of fluorescence
Where rockhounds find seelite
Classic worldwide localities
- Jachymov (Czech Republic)
- Schneeberg (Germany)
- Johanngeorgenstadt (Germany)
Field-hunting tip
Look in hydrothermal uranium-bearing veins country — that is the host setting where seelite typically forms. If you start seeing uraninite, proustite, arsenopyrite in float, you are in the right ground. Field specimens usually show a platy crystals, crusts habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find seelite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
