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.

Hardness

Mohs

Luster

Vitreous

Streak

White

Transparency

Semitransparent

mineralrare

Seelite

Hardness: ~3
Luster: Vitreous
Streak: White
Transparency: Semitransparent

Is this seelite?

5-step field check

Run through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.

1
Test the hardness
Try to scratch seelite with a known reference. Seelite sits at Mohs ~3, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Streak: white.
3
Read the luster
Hold the specimen under a strong light. Luster: vitreous.
4
Match the color range
Compare against the expected color range: canary-yellow, apple-green.
5
Look at form & habit
Crystal 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.

mineral

Autunite

Mohs 2-2.5

How to tell apart: Streak differs, so Seelite leaves white, Autunite leaves pale yellow.

How to tell apart: Streak differs, so Seelite leaves white, Meta-autunite leaves yellow; luster reads vitreous on Seelite and pearly to dull on Meta-autunite.

How to tell apart: Streak differs, so Seelite leaves white, Torbernite leaves pale green.

Compare →

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: ~3
Density: 3.70 g/cm³
Colors: Canary-yellow Apple-green
Streak: White
Luster: Vitreous
Transparency: Semitransparent
Crystal system: Monoclinic
Crystal habit: Platy crystals, crusts
Cleavage: Perfect
Fluorescence: Bright yellow under SW UV
Rarity: Rare
Uses: Collector
Host rock: A rare mineral in the oxidation zone of uranium-bearing hydrothermal deposits

Where rockhounds find seelite

Classic worldwide localities

Talmessi mine, 35 km west of Anarak, Iran
Rabéjac uranium deposit, seven km south-southeast of Lodève, Hérault, France

Field-hunting tip

Where it forms: A rare mineral in the oxidation zone of uranium-bearing hydrothermal deposits. If you start seeing annabergite, talmessite, zaratite in float, you are in the right ground. Typical habit: platy crystals, crusts. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify seelite?+

Mohs hardness is ~3. Luster: vitreous. The streak is white. Common colors include canary-yellow, apple-green.

Where is seelite found?+

Notable localities include Talmessi mine, 35 km west of Anarak, Iran; Rabéjac uranium deposit, seven km south-southeast of Lodève, Hérault, France.

Is seelite safe to handle?+

Seelite contains arsenic and uranium or thorium and calls for real care. Contains uranium and arsenic. Radioactive; requires proper shielded storage. Avoid dust inhalation or skin contact.

What rocks look like seelite?+

Seelite is most often confused with Autunite, Meta-autunite, Torbernite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with seelite?+

Seelite commonly co-occurs with Annabergite, Talmessite, Zaratite, Uranospinite, Zeunerite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does seelite form in?+

Where it forms: A rare mineral in the oxidation zone of uranium-bearing hydrothermal deposits. Working float back to the host body is the standard way to chase a fresh occurrence.

What is seelite used for?+

Seelite is used in collector.

Find seelite on the map

RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.