Yttrialite-(Y) is a rare yttrium-thorium silicate mineral typically found in granite pegmatites. It is often metamict due to radiation damage, meaning its internal crystal structure is partially destroyed, resulting in an amorphous appearance that is frequently found associated with other rare-earth minerals.

Hardness

6.5

Mohs

Luster

Vitreous

Streak

White

Transparency

Translucent

mineralrareGadolinite Group family

Yttrialite-(Y)

Hardness: 6.5
Luster: Vitreous
Streak: White
Transparency: Translucent

Is this yttrialite-(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 yttrialite-(y) with a known reference. Yttrialite-(Y) sits at Mohs 6.5 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Yttrialite-(Y) leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Yttrialite-(Y) typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: olive-green, brownish-yellow, black.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: massive, irregular grains.

Often confused with

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

Often found alongside yttrialite-(y)

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

All properties

Chemical formula: (Y,Th)₂Si₂O₇
Mohs hardness: 6.5
Density: 4.6-4.8 g/cm³
Colors: Olive-green Brownish-yellow Black
Streak: White
Luster: Vitreous
Transparency: Translucent
Crystal system: Monoclinic
Crystal habit: Massive, Irregular Grains
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: Granite Pegmatites
Typical price: $50-300 per specimen

Where rockhounds find yttrialite-(y)

Classic worldwide localities

Llano County, Texas, USA
Hitachi, Japan
Hittero, Norway

Field-hunting tip

Look in granite pegmatites country — that is the host setting where yttrialite-(y) typically forms. If you start seeing gadolinite, fergusonite, thorite in float, you are in the right ground. Field specimens usually show a massive, irregular grains habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify yttrialite-(y)?+

Mohs hardness is 6.5. It typically shows a vitreous luster. The streak is white. Common colors include olive-green, brownish-yellow, black.

Where is yttrialite-(y) found?+

Notable localities include Llano County, Texas, USA; Hitachi, Japan; Hittero, Norway.

How much is yttrialite-(y) worth?+

Typical asking prices fall in the range of $50-300 per specimen. Quality, size, and provenance can move individual specimens well outside that range.

Is yttrialite-(y) safe to handle?+

This mineral is radioactive. Contains thorium and rare earth elements; store in a lead-lined container or away from other specimens and handle with care, washing hands thoroughly after contact. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like yttrialite-(y)?+

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

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

Yttrialite-(Y) commonly co-occurs with Gadolinite, Fergusonite, Thorite, Zircon. Spotting any of these in float or country rock is a useful trip signal.

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

Yttrialite-(Y) typically forms in granite pegmatites. Working float back to the host body is the standard way to chase a fresh occurrence.

What is yttrialite-(y) used for?+

Yttrialite-(Y) is used in collector.

Find yttrialite-(y) on the map

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