Thomasclarkite-(Y) is an extremely rare carbonate mineral found primarily in the alkaline rocks of the Poudrette quarry at Mont Saint-Hilaire. It typically forms thin, white to colorless platy crystals and is highly prized by advanced micromount collectors due to its restricted type locality.
Is this thomasclarkite-(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 thomasclarkite-(y) with a known reference. Thomasclarkite-(Y) sits at Mohs 2-3, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: white.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: white, yellow.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: pseudo tetragonal.
Often confused with
Thomasclarkite-(Y) vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside thomasclarkite-(y)
Minerals reported to co-occur with thomasclarkite-(y). Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- NaY(HCO₃)(OH)₃·4H₂O
- Mohs hardness
- 2-3
- Density
- 2.30 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Semitransparent
- Crystal system
- Monoclinic
- Crystal habit
- Pseudo tetragonal
- Cleavage
- Perfect on {010}; a parting on {101}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Rarely in a pegmatite dike associated with an intrusive alkalic gabbro-syenite complex
Where rockhounds find thomasclarkite-(y)
Classic worldwide localities
- Mont Saint-Hilaire, Quebec, Canada
Field-hunting tip
Where it forms: Rarely in a pegmatite dike associated with an intrusive alkalic gabbro-syenite complex. If you start seeing aegirine, albite, analcime in float, you are in the right ground. Typical habit: pseudo tetragonal. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify thomasclarkite-(y)?+
Where is thomasclarkite-(y) found?+
What rocks look like thomasclarkite-(y)?+
What minerals are found with thomasclarkite-(y)?+
What kind of rock does thomasclarkite-(y) form in?+
What is thomasclarkite-(y) used for?+
Find thomasclarkite-(y) on the map
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