Moydite-(Y) is an exceptionally rare yttrium borate mineral typically found as small, platy, or radiating crystals in pegmatites. It is primarily identified by its characteristic association with rare-earth element minerals and requires micro-analysis for definitive confirmation by most collectors.
Is this moydite-(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 moydite-(y) with a known reference. Moydite-(Y) sits at Mohs 1-2, 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: yellow.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: platy crystals, radial aggregates.
Often confused with
Moydite-(Y) vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside moydite-(y)
Minerals reported to co-occur with moydite-(y). Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Y(B(OH)₄)CO₃
- Mohs hardness
- 1-2
- Density
- 3.13 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Orthorhombic
- Crystal habit
- Platy crystals, radial aggregates
- Cleavage
- Good on {010}; poor on {101}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A rare secondary mineral in quartz in a zoned granite pegmatite
Where rockhounds find moydite-(y)
Classic worldwide localities
- Evans-Lou quarry, near Wakefield Lake, Quebec, Canada
Field-hunting tip
Where it forms: A rare secondary mineral in quartz in a zoned granite pegmatite. If you start seeing hellandite, kainosite, lokkaite in float, you are in the right ground. Typical habit: platy crystals, radial aggregates. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify moydite-(y)?+
Where is moydite-(y) found?+
What rocks look like moydite-(y)?+
What minerals are found with moydite-(y)?+
What kind of rock does moydite-(y) form in?+
What is moydite-(y) used for?+
Find moydite-(y) on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
