Dewindtite is a secondary uranium phosphate mineral that typically forms as bright yellow, thin platy crystals or powdery crusts. It is most commonly found in the oxidized zones of uranium-rich hydrothermal deposits where lead is present. Due to its high radioactivity and toxicity, it is strictly a specimen for experienced collectors who follow proper safety protocols.

Hardness

2.5-3

Mohs

Luster

Pearly

Streak

Pale yellow

Transparency

Semitransparent

mineralrarePhosphuranylite Group family

Dewindtite

Also: Dewindtite (of Schoep and Wambeke)

Hardness: 2.5-3
Luster: Pearly
Streak: Pale yellow
Transparency: Semitransparent

Is this dewindtite?

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 dewindtite with a known reference. Dewindtite sits at Mohs 2.5-3, 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: pearly.
4
Match the color range
Compare against the expected color range: greenish yellow, yellow, light yellow.
5
Look at form & habit
Crystal system: orthorhombic. Typical habit: pulverulent, striated, tabular.

Often confused with

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

mineral

Autunite

Mohs 2-2.5

How to tell apart: Luster reads pearly on Dewindtite and vitreous, pearly on {001} on Autunite.

How to tell apart: Luster reads pearly on Dewindtite and vitreous, subadamantine, waxy, pearly on cleavages; becoming dull on dehydration to metatorbernite on Torbernite.

How to tell apart: Streak differs, so Dewindtite leaves pale yellow, Phosphuranylite leaves light yellow; luster reads pearly on Dewindtite and vitreous to pearly on Phosphuranylite.

Compare →

Often found alongside dewindtite

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

All properties

Chemical formula: Pb₃(UO₂)₆(PO₄)₄O₂(OH)₂·12H₂O
Mohs hardness: 2.5-3
Density: 5.03 g/cm³
Colors: Greenish yellow Yellow Light yellow
Streak: Pale yellow
Luster: Pearly
Transparency: Semitransparent
Crystal system: Orthorhombic
Crystal habit: Pulverulent, striated, tabular
Cleavage: {100}, perfect
Fluorescence: Green under SW and LW UV
Rarity: Rare
Uses: Collector
Host rock: A rare secondary mineral formed by alteration of uraninite or earlier-formed secondary uranium minerals

Where rockhounds find dewindtite

Classic worldwide localities

Shinkolobwe and Swambo, Katanga Province, Congo (Shaba Province, Zaire)
Wölsendorf, Bavaria, and on the Streuberg, near Bergen, and at Schneeberg, Saxony, Germany
La Faye, near Grury, Saône-et-Loire, and at Kerségalec-en-Lignol, Morbihan, France
Jáchymov (Joachimsthal), Czech Republic
Urgeiriça, Portugal
Takwa and Lac Indicateur areas, Quebec, Canada

Field-hunting tip

Where it forms: A rare secondary mineral formed by alteration of uraninite or earlier-formed secondary uranium minerals. If you start seeing torbernite, parsonsite, dumontite in float, you are in the right ground. Typical habit: pulverulent, striated, tabular. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify dewindtite?+

Mohs hardness is 2.5-3. Luster: pearly. The streak is pale yellow. Common colors include greenish yellow, yellow, light yellow.

Where is dewindtite found?+

Notable localities include Shinkolobwe and Swambo, Katanga Province, Congo (Shaba Province, Zaire); Wölsendorf, Bavaria, and on the Streuberg, near Bergen, and at Schneeberg, Saxony, Germany; La Faye, near Grury, Saône-et-Loire, and at Kerségalec-en-Lignol, Morbihan, France; Jáchymov (Joachimsthal), Czech Republic; Urgeiriça, Portugal.

Is dewindtite safe to handle?+

Dewindtite contains lead and uranium or thorium and calls for real care. This mineral is radioactive and contains lead. Handle with gloves, avoid inhaling dust, store in a sealed lead-lined container, and wash hands thoroughly after handling.

What rocks look like dewindtite?+

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

What minerals are found with dewindtite?+

Dewindtite commonly co-occurs with Torbernite, Parsonsite, Dumontite, Uraninite, Bergenite, Autunite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does dewindtite form in?+

Where it forms: A rare secondary mineral formed by alteration of uraninite or earlier-formed secondary uranium minerals. Working float back to the host body is the standard way to chase a fresh occurrence.

What is dewindtite used for?+

Dewindtite is used in collector.

Find dewindtite on the map

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