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Petscheckite is a rare uranium-bearing mineral often found in highly evolved granitic pegmatites. It is typically identified by its dark, submetallic appearance and its distinct radioactive signature, which often causes surrounding minerals to exhibit radiation damage halos.

Hardness
~5
Mohs
Luster
Metallic
Streak
Brownish black
Transparency
Opaque

Is this petscheckite?

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 petscheckite with a known reference. Petscheckite sits at Mohs ~5, softer than the next harder reference, harder than the previous one.
  • 2
    Check the streak
    Drag the specimen across an unglazed porcelain plate. Streak: brownish black.
  • 3
    Read the luster
    Hold the specimen under a strong light. Luster: metallic.
  • 4
    Match the color range
    Compare against the expected color range: black.
  • 5
    Look at form & habit
    Crystal system: trigonal. Typical habit: metamict.

Often confused with

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

Euxenite-(Y) mineral
mineral
Euxenite-(Y)
Mohs 5.5-6.5

How to tell apart: Streak differs, so Petscheckite leaves brownish black, Euxenite-(Y) leaves yellowish, grayish, or reddish brown; luster reads metallic on Petscheckite and brilliant submetallic, waxy to resinous on fractures on Euxenite-(Y).

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Often found alongside petscheckite

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

All properties

Chemical formula
UFeNb₂O₈
Mohs hardness
~5
Density
5.5 g/cm³
Colors
Black
Streak
Brownish black
Luster
Metallic
Transparency
Opaque
Crystal system
Trigonal
Crystal habit
Metamict
Cleavage
None
Rarity
Rare
Uses
Collector
Host rock
An accessory mineral in a zoned pegmatite

Where rockhounds find petscheckite

Classic worldwide localities

  • Antsakoa I pegmatite, near Berere, about 40 km northeast of Tsaratanana, Madagascar

Field-hunting tip

Where it forms: An accessory mineral in a zoned pegmatite. If you start seeing magnetite, columbite, liandratite in float, you are in the right ground. Typical habit: metamict. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify petscheckite?+
Mohs hardness is ~5. Luster: metallic. The streak is brownish black. Common colors include black.
Where is petscheckite found?+
Notable localities include Antsakoa I pegmatite, near Berere, about 40 km northeast of Tsaratanana, Madagascar.
Is petscheckite safe to handle?+
Petscheckite contains uranium or thorium and calls for real care. Due to its high uranium content, this mineral is significantly radioactive. Collectors should store it in a lead-lined container, avoid ingestion or inhalation of dust, and wash hands thoroughly after handling.
What rocks look like petscheckite?+
Petscheckite is most often confused with Euxenite-(Y). A quick hardness test and a streak check separate the look-alikes faster than color alone.
What minerals are found with petscheckite?+
Petscheckite commonly co-occurs with Magnetite, Columbite, Liandratite, Pyrochlore, Strüverite, Monazite. Spotting any of these in float or country rock is a useful trip signal.
What kind of rock does petscheckite form in?+
Where it forms: An accessory mineral in a zoned pegmatite. Working float back to the host body is the standard way to chase a fresh occurrence.
What is petscheckite used for?+
Petscheckite is used in collector.

Find petscheckite on the map

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