Fermiite is a rare secondary uranium sulfate mineral discovered in the uranium-bearing sandstones of Utah. It typically forms as delicate, bright yellow platy crystals or laths and is highly prized by collectors for its intense fluorescence under ultraviolet light.

Hardness

Mohs

Luster

Pearly

Streak

Yellow

Transparency

Translucent

mineralrare

Fermiite

Hardness: 2
Luster: Pearly
Streak: Yellow
Transparency: Translucent

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Is this fermiite?

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 fermiite with a known reference. Fermiite sits at Mohs 2 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Fermiite leaves a yellow streak.
3
Read the luster
Hold the specimen under a strong light. Fermiite typically shows a pearly luster.
4
Match the color range
Compare against the expected color range: yellow, yellow-orange.
5
Look at form & habit
Crystal system: triclinic. Typical habit: platy crystals, lath-like aggregates.

Often confused with

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

How to tell apart: Streak differs — Fermiite leaves yellow, Johannite leaves pale green; luster reads pearly on Fermiite and vitreous on Johannite.

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Often found alongside fermiite

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

All properties

Chemical formula: Na₄(UO₂)(SO₄)₃·3H₂O
Mohs hardness: 2
Density: 3.55 g/cm³
Colors: Yellow Yellow-orange
Streak: Yellow
Luster: Pearly
Transparency: Translucent
Crystal system: Triclinic
Crystal habit: Platy Crystals, Lath-like Aggregates
Cleavage: Perfect in One Direction
Fluorescence: Bright Yellow-green Under UV Light
Rarity: Rare
Uses: Collector
Host rock: Uranium-bearing Sandstone
Typical price: $50-300 per specimen

Where rockhounds find fermiite

Classic worldwide localities

Blue Lizard Mine, Utah, USA

Field-hunting tip

Look in uranium-bearing sandstone country — that is the host setting where fermiite typically forms. If you start seeing zippeite, gypsum, johannite in float, you are in the right ground. Field specimens usually show a platy crystals, lath-like aggregates habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify fermiite?+

Mohs hardness is 2. It typically shows a pearly luster. The streak is yellow. Common colors include yellow, yellow-orange.

Where is fermiite found?+

Notable localities include Blue Lizard Mine, Utah, USA.

How much is fermiite worth?+

Typical asking prices fall in the range of $50-300 per specimen. Quality, size, and provenance can move individual specimens well outside that range.

Is fermiite safe to handle?+

This mineral is radioactive. It contains toxic constituents. Fermiite contains uranium, making it radioactive; handle with care, use gloves, avoid ingestion or inhalation of dust, and store in a shielded container. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like fermiite?+

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

What minerals are found with fermiite?+

Fermiite commonly co-occurs with Zippeite, Gypsum, Johannite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does fermiite form in?+

Fermiite typically forms in uranium-bearing sandstone. Working float back to the host body is the standard way to chase a fresh occurrence.

What is fermiite used for?+

Fermiite is used in collector.

Find fermiite on the map

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