Metanatroautunite is a rare secondary uranium mineral formed by the dehydration of natroautunite. It typically appears as bright yellow or yellow-green platy crusts and is highly sought after by collectors for its brilliant yellow-green fluorescence under ultraviolet light.

Hardness

2-2.5

Mohs

Luster

Vitreous, pearly on {001}

Streak

Yellow

Transparency

Semitransparent

mineralrareAutunite Group family

Metanatroautunite

Hardness: 2-2.5
Luster: Vitreous, pearly on {001}
Streak: Yellow
Transparency: Semitransparent

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Is this metanatroautunite?

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 metanatroautunite with a known reference. Metanatroautunite sits at Mohs 2-2.5, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Streak: yellow.
3
Read the luster
Hold the specimen under a strong light. Luster: vitreous, pearly on {001}.
4
Match the color range
Compare against the expected color range: lemon-yellow, lettuce-yellow, greenish yellow.
5
Look at form & habit
Crystal system: tetragonal. Typical habit: platy crystals, micaceous aggregates, crusts.

Often confused with

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

mineral

Autunite

Mohs 2-2.5

How to tell apart: Streak differs, so Metanatroautunite leaves yellow, Autunite leaves pale yellow.

How to tell apart: Streak differs, so Metanatroautunite leaves yellow, Torbernite leaves pale green.

How to tell apart: Luster reads vitreous, pearly on {001} on Metanatroautunite and pearly to dull on Meta-autunite.

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Often found alongside metanatroautunite

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

All properties

Chemical formula: Na₂(UO₂)₂(PO₄)₂·6H₂O
Mohs hardness: 2-2.5
Density: 3.62 g/cm³
Colors: Lemon-yellowLettuce-yellowGreenish yellow
Streak: Yellow
Luster: Vitreous, pearly on {001}
Transparency: Semitransparent
Crystal system: Tetragonal
Crystal habit: Platy crystals, micaceous aggregates, crusts
Cleavage: {001}, perfect; {100}, less perfect
Fluorescence: Yellow-green fluorescence under UV
Rarity: Rare
Uses: Collector
Host rock: In the oxidized zone of a uranium deposit in a granodiorite massif (Tajikistan)

Where rockhounds find metanatroautunite

Classic worldwide localities

Found in the Kuruk uranium deposit, 15 km northeast of Khodzhent, Samgar Steppe, northern Tajikistan
Lake Boga Granite, Victoria, Australia

Field-hunting tip

Where it forms: In the oxidized zone of a uranium deposit in a granodiorite massif (Tajikistan). If you start seeing schoepite, gypsum, kaolinite in float, you are in the right ground. Typical habit: platy crystals, micaceous aggregates, crusts. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify metanatroautunite?+

Mohs hardness is 2-2.5. Luster: vitreous, pearly on {001}. The streak is yellow. Common colors include lemon-yellow, lettuce-yellow, greenish yellow.

Where is metanatroautunite found?+

Notable localities include Found in the Kuruk uranium deposit, 15 km northeast of Khodzhent, Samgar Steppe, northern Tajikistan; Lake Boga Granite, Victoria, Australia.

Is metanatroautunite safe to handle?+

Metanatroautunite contains uranium or thorium and calls for real care. This mineral is radioactive and contains uranium; handle with care using gloves and store in a lead-lined container. Avoid inhaling dust or ingestion; wash hands thoroughly after handling.

What rocks look like metanatroautunite?+

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

What minerals are found with metanatroautunite?+

Metanatroautunite commonly co-occurs with Schoepite, Gypsum, Kaolinite, Limonite, Saleeite, Torbernite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does metanatroautunite form in?+

Where it forms: In the oxidized zone of a uranium deposit in a granodiorite massif (Tajikistan). Working float back to the host body is the standard way to chase a fresh occurrence.

What is metanatroautunite used for?+

Metanatroautunite is used in collector.

Find metanatroautunite on the map

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