Yttrotungstite-(Y) is an extremely rare secondary tungsten mineral typically found as an alteration product of ferberite or scheelite in oxidized zones. It generally forms soft, platy, or earthy masses that display a distinct pearly luster on cleavage surfaces.

Hardness

Mohs

Luster

Earthy

Streak

Yellow white

Transparency

Semitransparent

mineralrare

Yttrotungstite-(Y)

Hardness: 1
Luster: Earthy
Streak: Yellow white
Transparency: Semitransparent

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Is this yttrotungstite-(y)?

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 yttrotungstite-(y) with a known reference. Yttrotungstite-(Y) sits at Mohs 1, 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 white.
3
Read the luster
Hold the specimen under a strong light. Luster: earthy.
4
Match the color range
Compare against the expected color range: canary yellow, light yellow.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: earthy, encrustations, lath.

Often confused with

Yttrotungstite-(Y) vs. its common look-alikes, and how to tell them apart in the field.

mineral

Tungstite

Mohs 2.5

How to tell apart: Tungstite is the harder of the two (Mohs 2.5 vs. 1); luster reads earthy on Yttrotungstite-(Y) and resinous, pearly on cleavages on Tungstite.

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Often found alongside yttrotungstite-(y)

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

All properties

Chemical formula: YW₂O₇(OH)(H₂O)
Mohs hardness: 1
Density: 5.96 g/cm³
Colors: Canary yellow Light yellow
Streak: Yellow white
Luster: Earthy
Transparency: Semitransparent
Crystal system: Monoclinic
Crystal habit: Earthy, encrustations, lath
Cleavage: {010}, good; on {101}, probable, very poor
Rarity: Rare
Uses: Collector
Host rock: In eluvial cassiterite mines, probably altered from wolframite or scheelite

Where rockhounds find yttrotungstite-(y)

Classic worldwide localities

Kramat Pulai mine and at Tapah, Kinta district, Perak, Malaysia

Field-hunting tip

Where it forms: In eluvial cassiterite mines, probably altered from wolframite or scheelite. If you start seeing kaolinite, quartz, muscovite in float, you are in the right ground. Typical habit: earthy, encrustations, lath. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify yttrotungstite-(y)?+

Mohs hardness is 1. Luster: earthy. The streak is yellow white. Common colors include canary yellow, light yellow.

Where is yttrotungstite-(y) found?+

Notable localities include Kramat Pulai mine and at Tapah, Kinta district, Perak, Malaysia.

Is yttrotungstite-(y) safe to handle?+

Contains rare earth elements and may contain thorium inclusions; handle with care and wash hands after contact to avoid ingestion or inhalation of dust.

What rocks look like yttrotungstite-(y)?+

Yttrotungstite-(Y) is most often confused with Tungstite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with yttrotungstite-(y)?+

Yttrotungstite-(Y) commonly co-occurs with Kaolinite, Quartz, Muscovite, Hydrobiotite, Hematite, Cassiterite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does yttrotungstite-(y) form in?+

Where it forms: In eluvial cassiterite mines, probably altered from wolframite or scheelite. Working float back to the host body is the standard way to chase a fresh occurrence.

What is yttrotungstite-(y) used for?+

Yttrotungstite-(Y) is used in collector.

Find yttrotungstite-(y) on the map

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