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Yttrocrasite-(Y) is a rare yttrium-rich titano-niobate mineral that typically occurs as massive, opaque black grains. It is primarily found within granite pegmatites and is highly valued by radioactive mineral collectors due to its complex chemical composition and scarcity.

Hardness
5.5-6
Mohs
Luster
Bright pitchy to resinous
Streak
Reddish brown
Transparency
Opaque, transparent in thin fragments

Is this yttrocrasite-(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 yttrocrasite-(y) with a known reference. Yttrocrasite-(Y) sits at Mohs 5.5-6, softer than the next harder reference, harder than the previous one.
  • 2
    Check the streak
    Drag the specimen across an unglazed porcelain plate. Streak: reddish brown.
  • 3
    Read the luster
    Hold the specimen under a strong light. Luster: bright pitchy to resinous.
  • 4
    Match the color range
    Compare against the expected color range: black.
  • 5
    Look at form & habit
    Crystal system: orthorhombic. Typical habit: metamict.

Often confused with

Yttrocrasite-(Y) 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 Yttrocrasite-(Y) leaves reddish brown, Euxenite-(Y) leaves yellowish, grayish, or reddish brown; luster reads bright pitchy to resinous on Yttrocrasite-(Y) and brilliant submetallic, waxy to resinous on fractures on Euxenite-(Y).

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Often found alongside yttrocrasite-(y)

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

All properties

Chemical formula
(Y,Th,Ca,U)(Ti,Fe)₂(O,OH)₆
Mohs hardness
5.5-6
Density
4.80 g/cm³
Colors
Black
Streak
Reddish brown
Luster
Bright pitchy to resinous
Transparency
Opaque, transparent in thin fragments
Crystal system
Orthorhombic
Crystal habit
Metamict
Cleavage
None
Rarity
Rare
Uses
Collector
Host rock
In granite pegmatite

Where rockhounds find yttrocrasite-(y)

Classic worldwide localities

  • Burnet Co., Texas, about five km east of Baringer Hill, USA

Field-hunting tip

Where it forms: In granite pegmatite. If you start seeing allanite, quartz, microcline 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 yttrocrasite-(y)?+
Mohs hardness is 5.5-6. Luster: bright pitchy to resinous. The streak is reddish brown. Common colors include black.
Where is yttrocrasite-(y) found?+
Notable localities include Burnet Co., Texas, about five km east of Baringer Hill, USA.
Is yttrocrasite-(y) safe to handle?+
Yttrocrasite-(Y) contains uranium or thorium and calls for real care. Contains thorium and uranium; radioactive, requires safe handling, storage, and should not be kept in close proximity to living spaces or other sensitive materials.
What rocks look like yttrocrasite-(y)?+
Yttrocrasite-(Y) 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 yttrocrasite-(y)?+
Yttrocrasite-(Y) commonly co-occurs with Allanite, Quartz, Microcline, Biotite. Spotting any of these in float or country rock is a useful trip signal.
What kind of rock does yttrocrasite-(y) form in?+
Where it forms: In granite pegmatite. Working float back to the host body is the standard way to chase a fresh occurrence.
What is yttrocrasite-(y) used for?+
Yttrocrasite-(Y) is used in collector.

Find yttrocrasite-(y) on the map

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