Rowlandite-(Y) is a very rare yttrium silicate mineral typically found as massive, anhedral grains in granite pegmatites. It is visually similar to gadolinite and often occurs as an alteration product or in intimate association with other rare-earth-bearing silicates.
Is this rowlandite-(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 rowlandite-(y) with a known reference. Rowlandite-(Y) sits at Mohs 5.5-6.5, 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; waxy when altered.
- 4Match the color rangeCompare against the expected color range: gray white, light green.
- 5Look at form & habitCrystal system: triclinic. Typical habit: massive.
Often confused with
Rowlandite-(Y) vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Rowlandite-(Y) leaves white, Gadolinite-(Y) leaves greenish gray.
How to tell apart: Streak differs, so Rowlandite-(Y) leaves white, Allanite leaves gray; luster reads vitreous; waxy when altered on Rowlandite-(Y) and submetallic on Allanite.
Often found alongside rowlandite-(y)
Minerals reported to co-occur with rowlandite-(y). Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- FeY₄(Si₂O₇)₂F₂
- Mohs hardness
- 5.5-6.5
- Density
- 4.39 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous; waxy when altered
- Transparency
- Transparent in thin fragments
- Crystal system
- Triclinic
- Crystal habit
- Massive
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In some rare-earth-rich pegmatites
Where rockhounds find rowlandite-(y)
Classic worldwide localities
- Baringer Hill pegmatite, 26 km west of Burnet, Llano Co., and from Clear Creek, Burnet Co., Texas, USA
- Evans-Lou quarry, near Wakefield Lake, Quebec, Canada
Field-hunting tip
Where it forms: In some rare-earth-rich pegmatites. If you start seeing gadolinite, yttrialite in float, you are in the right ground. Typical habit: massive. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify rowlandite-(y)?+
Where is rowlandite-(y) found?+
Is rowlandite-(y) safe to handle?+
What rocks look like rowlandite-(y)?+
What minerals are found with rowlandite-(y)?+
What kind of rock does rowlandite-(y) form in?+
What is rowlandite-(y) used for?+
Find rowlandite-(y) on the map
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