Tanteuxenite-(Y) is a rare radioactive member of the euxenite group characterized by its dominant tantalum content. It typically occurs as black to dark brown prismatic crystals or massive inclusions within complex granite pegmatites.
Is this tanteuxenite-(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 tanteuxenite-(y) with a known reference. Tanteuxenite-(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: brownish gray.
- 3Read the lusterHold the specimen under a strong light. Luster: resinous.
- 4Match the color rangeCompare against the expected color range: brownish black.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: indistinct, metamict, tabular.
Often confused with
Tanteuxenite-(Y) vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Tanteuxenite-(Y) leaves brownish gray, Euxenite-(Y) leaves yellowish, grayish, or reddish brown; luster reads resinous on Tanteuxenite-(Y) and brilliant submetallic, waxy to resinous on fractures on Euxenite-(Y).
How to tell apart: Streak differs, so Tanteuxenite-(Y) leaves brownish gray, Samarskite-(Y) leaves dark reddish brown to black, yellow-brown; gray when altered; luster reads resinous on Tanteuxenite-(Y) and vitreous to resinous, may be submetallic, splendent; externally dull on Samarskite-(Y).
Often found alongside tanteuxenite-(y)
Minerals reported to co-occur with tanteuxenite-(y). Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Y(TaTi)O₆
- Mohs hardness
- 5.5-6
- Density
- 5.4-5.9 g/cm³
- Colors
- Streak
- Brownish gray
- Luster
- Resinous
- Transparency
- Opaque, transparent in thin fragments
- Crystal system
- Orthorhombic
- Crystal habit
- Indistinct, metamict, tabular
- Cleavage
- Indistinct
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A detrital mineral in tin placers (Western Australia); in a granite pegmatite (Craveggia, Italy)
Where rockhounds find tanteuxenite-(y)
Classic worldwide localities
- Eleys, 16 km south of Cooglegong, and at Woodstock, Pilbara district, Western Australia
- Piano del Lavonchio, near Craveggia, Val Vigezzo, Piedmont, Italy
- Ituri, Haut-Zaire Province, Congo (Zaire)
Field-hunting tip
Where it forms: A detrital mineral in tin placers (Western Australia); in a granite pegmatite (Craveggia, Italy). If you start seeing striiverite, columbite, ilmenite in float, you are in the right ground. Typical habit: indistinct, metamict, tabular. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify tanteuxenite-(y)?+
Where is tanteuxenite-(y) found?+
Is tanteuxenite-(y) safe to handle?+
What rocks look like tanteuxenite-(y)?+
What minerals are found with tanteuxenite-(y)?+
What kind of rock does tanteuxenite-(y) form in?+
What is tanteuxenite-(y) used for?+
Find tanteuxenite-(y) on the map
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