Trimounsite-(Y) is an exceptionally rare yttrium-bearing silicate mineral originally discovered in the Trimouns talc mine of France. It typically occurs as small tabular crystals within dolomitic marble environments associated with hydrothermal activity.
Is this trimounsite-(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 trimounsite-(y) with a known reference. Trimounsite-(Y) sits at Mohs 6-6.5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Trimounsite-(Y) leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Trimounsite-(Y) typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: yellow, brown, colorless.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: tabular crystals.
Often confused with
Trimounsite-(Y) vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Trimounsite-(Y) leaves white, Allanite leaves gray; luster reads vitreous on Trimounsite-(Y) and submetallic on Allanite.
How to tell apart: Luster reads vitreous on Trimounsite-(Y) and adamantine on Titanite.
Often found alongside trimounsite-(y)
Minerals reported to co-occur with trimounsite-(y). Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (Y,Ca)₄Ti(SiO₄)₂O₂(OH)₂
- Mohs hardness
- 6-6.5
- Density
- 4.67 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Tabular Crystals
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Dolomitic Marble
- Typical price
- $50-500 depending on specimen size and clarity
Where rockhounds find trimounsite-(y)
Classic worldwide localities
- Trimouns talc quarry, France
Field-hunting tip
Look in dolomitic marble country — that is the host setting where trimounsite-(y) typically forms. If you start seeing talc, dolomite, quartz in float, you are in the right ground. Field specimens usually show a tabular crystals habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify trimounsite-(y)?+
Where is trimounsite-(y) found?+
How much is trimounsite-(y) worth?+
What rocks look like trimounsite-(y)?+
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Find trimounsite-(y) on the map
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