Okanoganite-(Y) is an exceptionally rare rare-earth element silicate mineral found primarily in alkaline pegmatites. It is typically identified by its tabular crystal habit and distinct tan to pale pink coloration in the field, often occurring in association with other rare accessory minerals in radioactive pegmatite environments.
Is this okanoganite-(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 okanoganite-(y) with a known reference. Okanoganite-(Y) sits at Mohs 4, 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 dull.
- 4Match the color rangeCompare against the expected color range: light brown, light pink, white, yellow.
- 5Look at form & habitCrystal system: trigonal. Typical habit: pseudo tetragonal, twinning common.
Often confused with
Okanoganite-(Y) vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Allanite is the harder of the two (Mohs 5.5-6 vs. 4); streak differs, so Okanoganite-(Y) leaves white, Allanite leaves gray; luster reads vitreous to dull on Okanoganite-(Y) and submetallic on Allanite.
How to tell apart: Gadolinite-(Y) is the harder of the two (Mohs 6.5-7 vs. 4); streak differs, so Okanoganite-(Y) leaves white, Gadolinite-(Y) leaves greenish gray.
Often found alongside okanoganite-(y)
Minerals reported to co-occur with okanoganite-(y). Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (Y,REE,Ca,Na,Th)₁₆(Fe,Ti)(Si,B,P)₁₀(O,OH)₃₈F₁₀
- Mohs hardness
- 4
- Density
- 4.35 g/cm³
- Streak
- White
- Luster
- Vitreous to dull
- Transparency
- Transparent to translucent
- Crystal system
- Trigonal
- Crystal habit
- Pseudo tetragonal, twinning common
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In miarolitic cavities in a peralkalic arfvedsonite-bearing granite
Where rockhounds find okanoganite-(y)
Classic worldwide localities
- Golden Horn batholith, near Washington Pass, Okanogan Co., Washington, USA
Field-hunting tip
Where it forms: In miarolitic cavities in a peralkalic arfvedsonite-bearing granite. If you start seeing quartz, microcline, zircon in float, you are in the right ground. Typical habit: pseudo tetragonal, twinning common. Train your eye for that shape before scanning the outcrop.
Common questions
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Find okanoganite-(y) on the map
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