Tengerite-(Y) is a rare yttrium carbonate mineral typically found as an alteration product of other rare-earth minerals like gadolinite. It most commonly appears as white to yellowish-white earthy crusts or delicate platy aggregates in granitic pegmatites. Collectors look for it as a secondary coating on matrix rocks associated with pegmatite minerals.
Is this tengerite-(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 tengerite-(y) with a known reference. Tengerite-(Y) sits at Mohs 3.5, 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: dull, chalky.
- 4Match the color rangeCompare against the expected color range: white.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: fibrous, pulverulent.
Often confused with
Tengerite-(Y) vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Luster reads dull, chalky on Tengerite-(Y) and vitreous to pearly on Lanthanite-(Nd).
How to tell apart: Luster reads dull, chalky on Tengerite-(Y) and vitreous; pearly on cleavages and {0001} on Calcite.
How to tell apart: Luster reads dull, chalky on Tengerite-(Y) and vitreous to greasy on Bastnäsite.
Often found alongside tengerite-(y)
Minerals reported to co-occur with tengerite-(y). Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Y₂(CO₃)₃·nH₂O
- Mohs hardness
- 3.5
- Density
- 3.12 g/cm³
- Colors
- Streak
- White
- Luster
- Dull, chalky
- Transparency
- Semitransparent
- Crystal system
- Orthorhombic
- Crystal habit
- Fibrous, pulverulent
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- An alteration coating on yttrium-bearing minerals
Where rockhounds find tengerite-(y)
Classic worldwide localities
- Baringer Hill pegmatite, 26 km west of Burnet, and the Rode Ranch pegmatite, near Bluffton, Llano Co., and from the Clear Creek pegmatite, Burnet Co., Texas, USA
- Ytterby, on Resarö Island, near Vaxholm, and at Åskagen, Värmland, Sweden
- Rosås, Norway
- Pyörönmaa pegmatite, Kangasala, and Lövböle, Kemiö, Finland
- Iisaka and Suishoyama, Fukushima Prefecture, Japan
- Evans-Lou pegmatite, 32 km north of Hull, Quebec, Canada
Field-hunting tip
Where it forms: An alteration coating on yttrium-bearing minerals. If you start seeing gadolinite-, lokkaite-, kimuraite- in float, you are in the right ground. Typical habit: fibrous, pulverulent. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify tengerite-(y)?+
Where is tengerite-(y) found?+
What rocks look like tengerite-(y)?+
What minerals are found with tengerite-(y)?+
What kind of rock does tengerite-(y) form in?+
What is tengerite-(y) used for?+
Find tengerite-(y) on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
