Synchysite-(Y) is a rare rare-earth carbonate mineral typically found as small, thin platy crystals often exhibiting pseudo-hexagonal symmetry. It is most commonly identified by collectors in alkaline pegmatite environments or miarolitic cavities associated with other rare earth minerals.
Is this synchysite-(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 synchysite-(y) with a known reference. Synchysite-(Y) sits at Mohs ~4.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: brown.
- 3Read the lusterHold the specimen under a strong light. Luster: greasy.
- 4Match the color rangeCompare against the expected color range: reddish brown.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: massive.
Often confused with
Synchysite-(Y) vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Synchysite-(Y) leaves brown, Bastnäsite leaves white; luster reads greasy on Synchysite-(Y) and vitreous to greasy on Bastnäsite.
How to tell apart: Streak differs, so Synchysite-(Y) leaves brown, Synchysite-(Ce) leaves white; luster reads greasy on Synchysite-(Y) and vitreous to subadamantine, may be greasy on Synchysite-(Ce).
Often found alongside synchysite-(y)
Minerals reported to co-occur with synchysite-(y). Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CaY(CO₃)₂F
- Mohs hardness
- ~4.5
- Density
- 3.9 g/cm³
- Colors
- Streak
- Brown
- Luster
- Greasy
- Transparency
- Transparent to translucent
- Crystal system
- Monoclinic
- Crystal habit
- Massive
- Cleavage
- Distinct on {0001}
- Rarity
- Rare
- Uses
- Collector, Scientific research
- Host rock
- A rare hydrothermal accessory mineral in alkalic granites and granite pegmatites
Where rockhounds find synchysite-(y)
Classic worldwide localities
- Scrub Oaks iron mine, Mine Hill, 4 km west of Dover, Morris Co., New Jersey, USA
- Henry pegmatite, near Cotopaxi, Fremont Co., and the Big Bertha and White Cloud pegmatites, South Platte district, Jefferson Co., Colorado, USA
- Rib Mountain, Marathon Co., Wisconsin, USA
- Evans-Lou quarry, near Wakefield, Quebec, Canada
- Gallt y Wenallt, Gwynedd, Wales
- Bad Grund, Harz Mountains, Germany
Field-hunting tip
Where it forms: A rare hydrothermal accessory mineral in alkalic granites and granite pegmatites. If you start seeing kainosite, bastnäsite, xenotime 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 synchysite-(y)?+
Where is synchysite-(y) found?+
What rocks look like synchysite-(y)?+
What minerals are found with synchysite-(y)?+
What kind of rock does synchysite-(y) form in?+
What is synchysite-(y) used for?+
Find synchysite-(y) on the map
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