Formanite-(Y) is a rare yttrium tantalate mineral found primarily in granitic pegmatites. Collectors look for its characteristic brown to black prismatic crystals, which are often metamict due to internal radiation damage over geological time.
Is this formanite-(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 formanite-(y) with a known reference. Formanite-(Y) sits at Mohs 5.5-6.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Formanite-(Y) leaves a pale yellow streak.
- 3Read the lusterHold the specimen under a strong light. Formanite-(Y) typically shows a metallic to resinous to greasy luster.
- 4Match the color rangeCompare against the expected color range: yellow, brown, reddish-brown, black.
- 5Look at form & habitCrystal system: tetragonal. Typical habit: prismatic crystals, flattened, massive.
Often confused with
Formanite-(Y) vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Luster reads metallic to resinous to greasy on Formanite-(Y) and dull to vitreous to submetallic on Fergusonite-(Y).
How to tell apart: Streak differs, so Formanite-(Y) leaves pale yellow, Samarskite-(Y) leaves dark brown; luster reads metallic to resinous to greasy on Formanite-(Y) and submetallic on Samarskite-(Y).
How to tell apart: Streak differs, so Formanite-(Y) leaves pale yellow, Columbium Ore leaves dark red to black; luster reads metallic to resinous to greasy on Formanite-(Y) and submetallic on Columbium Ore.
Often found alongside formanite-(y)
Minerals reported to co-occur with formanite-(y). Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- YTaO₄
- Mohs hardness
- 5.5-6.5
- Density
- 6.5-7.1 g/cm³
- Streak
- Pale Yellow
- Luster
- Metallic to Resinous to Greasy
- Transparency
- Opaque
- Crystal system
- Tetragonal
- Crystal habit
- Prismatic Crystals, Flattened, Massive
- Cleavage
- {111}, Interrupted
- Rarity
- Rare
- Uses
- Collector, Geological Study
- Host rock
- Granite Pegmatites
Where rockhounds find formanite-(y)
Classic worldwide localities
- Norway
- Russia
- USA
- Canada
Field-hunting tip
Look in granite pegmatites country, the host setting where formanite-(y) typically forms. If you start seeing zircon, monazite, allanite in float, you are in the right ground. Field specimens usually show a prismatic crystals, flattened, massive habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify formanite-(y)?+
Where is formanite-(y) found?+
Is formanite-(y) safe to handle?+
What rocks look like formanite-(y)?+
What minerals are found with formanite-(y)?+
What kind of rock does formanite-(y) form in?+
What is formanite-(y) used for?+
Find formanite-(y) on the map
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