Metauranopilite is a rare uranyl sulfate mineral that typically forms as an alteration product in uranium-rich environments. Collectors seek it primarily for its intense, bright yellow-green fluorescence under long-wave ultraviolet light, which makes it a standout display piece for radioactive mineral collections.

Hardness

2-3

Mohs

Luster

Vitreous

Streak

Pale yellow

Transparency

Semitransparent

mineralrareUranopilite Group family

Metauranopilite

Hardness: 2-3
Luster: Vitreous
Streak: Pale yellow
Transparency: Semitransparent

No image

Is this metauranopilite?

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 metauranopilite with a known reference. Metauranopilite sits at Mohs 2-3, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Streak: pale yellow.
3
Read the luster
Hold the specimen under a strong light. Luster: vitreous.
4
Match the color range
Compare against the expected color range: yellow, gray, grayish green, brownish.
5
Look at form & habit
Crystal system: orthorhombic. Typical habit: acicular, tabular.

Often confused with

Metauranopilite vs. its common look-alikes, and how to tell them apart in the field.

mineral

Uranopilite

Mohs 2.5

How to tell apart: Luster reads vitreous on Metauranopilite and silky on Uranopilite.

How to tell apart: Streak differs, so Metauranopilite leaves pale yellow, Zippeite leaves yellow white.

Often found alongside metauranopilite

Minerals reported to co-occur with metauranopilite. Spotting these in float or country rock is a strong cue you are in the right ground.

Uranopilite
mineral · Mohs 2.5

All properties

Chemical formula: (UO₂)₆SO₄(OH)₁₀·5H₂O
Mohs hardness: 2-3
Colors: Yellow Gray Grayish green Brownish
Streak: Pale yellow
Luster: Vitreous
Transparency: Semitransparent
Crystal system: Orthorhombic
Crystal habit: Acicular, tabular
Cleavage: Perfect
Fluorescence: Yellow green under SW UV
Rarity: Rare
Uses: Collector
Host rock: On a museum specimen from a uranium-bearing hydrothermal ore deposit [may = jáchymovite]

Where rockhounds find metauranopilite

Classic worldwide localities

Jáchymov (Joachimsthal), Czech Republic

Field-hunting tip

Where it forms: On a museum specimen from a uranium-bearing hydrothermal ore deposit [may = jáchymovite]. If you start seeing uranopilite in float, you are in the right ground. Typical habit: acicular, tabular. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify metauranopilite?+

Mohs hardness is 2-3. Luster: vitreous. The streak is pale yellow. Common colors include yellow, gray, grayish green, brownish.

Where is metauranopilite found?+

Notable localities include Jáchymov (Joachimsthal), Czech Republic.

Is metauranopilite safe to handle?+

Metauranopilite contains uranium or thorium and calls for real care. Radioactive material; emits ionizing radiation. Wash hands thoroughly after handling, avoid ingestion or inhalation of dust, and store in a sealed lead-lined container away from living spaces.

What rocks look like metauranopilite?+

Metauranopilite is most often confused with Uranopilite, Zippeite, Autunite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with metauranopilite?+

Metauranopilite commonly co-occurs with Uranopilite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does metauranopilite form in?+

Where it forms: On a museum specimen from a uranium-bearing hydrothermal ore deposit [may = jáchymovite]. Working float back to the host body is the standard way to chase a fresh occurrence.

What is metauranopilite used for?+

Metauranopilite is used in collector.

Find metauranopilite on the map

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