Kimuraite-(Y) is an extremely rare yttrium calcium carbonate mineral typically found in small, thin platy crystals. It is most notable for occurring primarily in specific alkaline igneous environments in Japan. Due to its scarcity, it is considered a premier prize for advanced rare-earth mineral collectors.
Is this kimuraite-(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 kimuraite-(y) with a known reference. Kimuraite-(Y) sits at Mohs 2.5, 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 to silky on cleavages.
- 4Match the color rangeCompare against the expected color range: white, light purple pink, light pink.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: aggregates, spherical.
Often confused with
Kimuraite-(Y) vs. its common look-alikes, and how to tell them apart in the field.
All properties
- Chemical formula
- CaY₂ (CO₃)₄·6H₂O
- Mohs hardness
- 2.5
- Density
- 2.6 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous to silky on cleavages
- Transparency
- Semitransparent
- Crystal system
- Orthorhombic
- Crystal habit
- Aggregates, spherical
- Cleavage
- Perfect on {010}
- Fluorescence
- Reddish purple under SW UV; purple under LW UV
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In fissures in an alkali olivine basalt
Where rockhounds find kimuraite-(y)
Classic worldwide localities
- Kirigo and Niikoba, Higashi-Matsuura district, Saga Prefecture, Japan
Field-hunting tip
Where it forms: In fissures in an alkali olivine basalt. If you start seeing lanthanite-, lokkaite-, kozoite- in float, you are in the right ground. Typical habit: aggregates, spherical. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify kimuraite-(y)?+
Where is kimuraite-(y) found?+
What rocks look like kimuraite-(y)?+
What minerals are found with kimuraite-(y)?+
What kind of rock does kimuraite-(y) form in?+
What is kimuraite-(y) used for?+
Find kimuraite-(y) on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
