Tantalaeschynite-(Y) is a rare radioactive mineral occurring primarily in granitic pegmatites. It typically forms as dark, submetallic, prismatic crystals that are frequently metamict due to internal radiation damage.
Is this tantalaeschynite-(y)?
5-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Test the hardnessTry to scratch tantalaeschynite-(y) with a known reference. Tantalaeschynite-(Y) sits at Mohs 5.5-6, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: pale yellowish brown.
- 3Read the lusterHold the specimen under a strong light. Luster: resinous.
- 4Match the color rangeCompare against the expected color range: black, brownish black.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: metamict.
Often confused with
Tantalaeschynite-(Y) vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Tantalaeschynite-(Y) leaves pale yellowish brown, Euxenite-(Y) leaves yellowish, grayish, or reddish brown; luster reads resinous on Tantalaeschynite-(Y) and brilliant submetallic, waxy to resinous on fractures on Euxenite-(Y).
How to tell apart: Streak differs, so Tantalaeschynite-(Y) leaves pale yellowish brown, Columbite leaves blackish brown; luster reads resinous on Tantalaeschynite-(Y) and submetallic on Columbite.
Often found alongside tantalaeschynite-(y)
Minerals reported to co-occur with tantalaeschynite-(y). Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Y(TiTa)O₆
- Mohs hardness
- 5.5-6
- Density
- 5.75-6.13 g/cm³
- Colors
- Streak
- Pale yellowish brown
- Luster
- Resinous
- Transparency
- Transparent
- Crystal system
- Orthorhombic
- Crystal habit
- Metamict
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In a pegmatite
Where rockhounds find tantalaeschynite-(y)
Classic worldwide localities
- Raposa pegmatite, near São José do Sabugí, Paraíba, Brazil
Field-hunting tip
Where it forms: In a pegmatite. If you start seeing quartz, microcline, biotite 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 tantalaeschynite-(y)?+
Where is tantalaeschynite-(y) found?+
Is tantalaeschynite-(y) safe to handle?+
What rocks look like tantalaeschynite-(y)?+
What minerals are found with tantalaeschynite-(y)?+
What kind of rock does tantalaeschynite-(y) form in?+
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Find tantalaeschynite-(y) on the map
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