Iimoriite-(Y) is a rare yttrium-bearing silicate-carbonate mineral first discovered in the Iimori mine in Japan. It typically occurs as massive, granular aggregates in granitic pegmatites and is often associated with other rare-earth minerals like xenotime and fergusonite.
Is this iimoriite-(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 iimoriite-(y) with a known reference. Iimoriite-(Y) sits at Mohs 5.5-6, 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 resinous.
- 4Match the color rangeCompare against the expected color range: white, brown, colorless, gray pink, purple gray.
- 5Look at form & habitCrystal system: triclinic. Typical habit: granular, massive, rarely distinct crystals.
Often confused with
Iimoriite-(Y) vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside iimoriite-(y)
Minerals reported to co-occur with iimoriite-(y). Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Y₂(SiO₄)(CO₃)
- Mohs hardness
- 5.5-6
- Density
- 4.47 g/cm³
- Streak
- White
- Luster
- Vitreous to resinous
- Transparency
- Semitransparent
- Crystal system
- Triclinic
- Crystal habit
- Granular, massive, rarely distinct crystals
- Cleavage
- Distinct on {011}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In quartz-microcline pegmatite (Fusamata, Japan); in veins in peralkalic riebeckite-aegirine granite (Bokan Mountain, Alaska, USA)
Where rockhounds find iimoriite-(y)
Classic worldwide localities
- I and L No. 4 claim, Bokan Mountain, Prince of Wales Island, Alaska, USA
- Fusamata and Suishoyama, Fukushima Prefecture, and Soraku, Kyoto Prefecture, Japan
Field-hunting tip
Where it forms: In quartz-microcline pegmatite (Fusamata, Japan); in veins in peralkalic riebeckite-aegirine granite (Bokan Mountain, Alaska, USA). If you start seeing biotite, monazite, fergusonite in float, you are in the right ground. Typical habit: granular, massive, rarely distinct crystals. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify iimoriite-(y)?+
Where is iimoriite-(y) found?+
Is iimoriite-(y) safe to handle?+
What rocks look like iimoriite-(y)?+
What minerals are found with iimoriite-(y)?+
What kind of rock does iimoriite-(y) form in?+
What is iimoriite-(y) used for?+
Find iimoriite-(y) on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
