Donnayite-(Y) is an exceedingly rare carbonate mineral typically found in the miarolitic cavities of alkaline complexes. Collectors usually identify it by its pseudo-hexagonal, tabular crystal habit and its occurrence alongside other rare earth element minerals in complex pegmatite environments.
Is this donnayite-(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 donnayite-(y) with a known reference. Donnayite-(Y) sits at Mohs 3 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Donnayite-(Y) leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Donnayite-(Y) typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: colorless, white, yellow, pale brownish.
- 5Look at form & habitCrystal system: triclinic. Typical habit: pseudo-hexagonal dipyramidal crystals.
Often confused with
Donnayite-(Y) vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside donnayite-(y)
Minerals reported to co-occur with donnayite-(y). Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- NaSrCaY(CO₃)₄·3H₂O
- Mohs hardness
- 3
- Density
- 3.37 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Triclinic
- Crystal habit
- Pseudo-hexagonal Dipyramidal Crystals
- Cleavage
- Distinct On {001}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Alkaline Igneous Rocks (agpaitic Pegmatites)
- Typical price
- $50-500 depending on crystal size and quality
Where rockhounds find donnayite-(y)
Classic worldwide localities
- Mont Saint-Hilaire, Quebec, Canada
Field-hunting tip
Look in alkaline igneous rocks (agpaitic pegmatites) country — that is the host setting where donnayite-(y) typically forms. If you start seeing microcline, sodalite, aegirine in float, you are in the right ground. Field specimens usually show a pseudo-hexagonal dipyramidal crystals habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify donnayite-(y)?+
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Find donnayite-(y) on the map
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