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Leószilárdite is a rare uranyl carbonate mineral typically found as small, bright yellow tabular crystals or crusts in uranium-bearing sandstone. It was discovered in the San Rafael Swell of Utah and is highly prized by advanced collectors for its rarity and complex chemical composition.

Hardness
2
Mohs
Luster
Vitreous
Streak
Pale Yellow
Transparency
Transparent

Is this leószilárdite?

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 leószilárdite with a known reference. Leószilárdite 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. Leószilárdite leaves a pale yellow streak.
  • 3
    Read the luster
    Hold the specimen under a strong light. Leószilárdite typically shows a vitreous luster.
  • 4
    Match the color range
    Compare against the expected color range: yellow.
  • 5
    Look at form & habit
    Crystal system: monoclinic. Typical habit: tabular crystals, crusts.

Often confused with

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

Liebigite mineral
mineral
Liebigite
Mohs 2.5
Compare →
Schröckingerite mineral — Schrockingerite 199667
mineral
Schröckingerite
Mohs 2.5

How to tell apart: Luster reads vitreous on Leószilárdite and pearly on Schröckingerite.

Compare →

Often found alongside leószilárdite

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

All properties

Chemical formula
Na₆Mg(UO₂)₂(CO₃)₆·6H₂O
Mohs hardness
2
Density
2.98 g/cm³
Colors
Yellow
Streak
Pale Yellow
Luster
Vitreous
Transparency
Transparent
Crystal system
Monoclinic
Crystal habit
Tabular Crystals, Crusts
Cleavage
Good
Rarity
Rare
Uses
Collector
Host rock
Sedimentary Sandstone
Typical price
$50-300 thumbnail

Where rockhounds find leószilárdite

Classic worldwide localities

  • San Rafael Swell, Utah, USA

Field-hunting tip

Look in sedimentary sandstone country — that is the host setting where leószilárdite typically forms. If you start seeing uraninite, gypsum in float, you are in the right ground. Field specimens usually show a tabular crystals, crusts habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify leószilárdite?+
Mohs hardness is 2. It typically shows a vitreous luster. The streak is pale yellow. Common colors include yellow.
Where is leószilárdite found?+
Notable localities include San Rafael Swell, Utah, USA.
How much is leószilárdite worth?+
Typical asking prices fall in the range of $50-300 thumbnail. Quality, size, and provenance can move individual specimens well outside that range.
Is leószilárdite safe to handle?+
This mineral is radioactive. It contains toxic constituents. This mineral contains uranium and is radioactive; handle with gloves and store in a sealed lead-lined container away from living areas. Avoid inhaling dust or ingestion. Handle with care, avoid grinding or breathing dust, and store separately.
What rocks look like leószilárdite?+
Leószilárdite is most often confused with Liebigite, Schröckingerite. A quick hardness test and a streak check separate the look-alikes faster than color alone.
What minerals are found with leószilárdite?+
Leószilárdite commonly co-occurs with uraninite, gypsum. Spotting any of these in float or country rock is a useful trip signal.
What kind of rock does leószilárdite form in?+
Leószilárdite typically forms in sedimentary sandstone. Working float back to the host body is the standard way to chase a fresh occurrence.
What is leószilárdite used for?+
Leószilárdite is used in collector.

Find leószilárdite on the map

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