Tritomite-(Y) is a rare radioactive borosilicate mineral found primarily in alkaline syenite pegmatites. It usually occurs as massive, dull grains rather than well-formed crystals, often requiring professional testing to distinguish from other similar rare-earth minerals.
Is this tritomite-(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 tritomite-(y) with a known reference. Tritomite-(Y) sits at Mohs 3.5-6.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: greenish gray.
- 3Read the lusterHold the specimen under a strong light. Luster: weakly vitreous to resinous.
- 4Match the color rangeCompare against the expected color range: greenish black, dark green black, reddish brown.
- 5Look at form & habitCrystal system: hexagonal. Typical habit: metamict, pyramidal.
Often confused with
Tritomite-(Y) vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Tritomite-(Y) leaves greenish gray, Apatite leaves white; luster reads weakly vitreous to resinous on Tritomite-(Y) and vitreous on Apatite.
How to tell apart: Streak differs, so Tritomite-(Y) leaves greenish gray, Monazite leaves white; luster reads weakly vitreous to resinous on Tritomite-(Y) and resinous on Monazite.
Often found alongside tritomite-(y)
Minerals reported to co-occur with tritomite-(y). Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Y₅(SiO₄,BO₄)₃(O,OH,F)
- Mohs hardness
- 3.5-6.5
- Density
- 3.05-3.40 g/cm³
- Colors
- Streak
- Greenish gray
- Luster
- Weakly vitreous to resinous
- Transparency
- Translucent in thin fragments
- Crystal system
- Hexagonal
- Crystal habit
- Metamict, pyramidal
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In granite pegmatites and pegmatite veins cutting pyroxenite
Where rockhounds find tritomite-(y)
Classic worldwide localities
- Cranberry Lake, Sussex Co., New Jersey, USA
- A prospect pit in Cardi® township, and in the Faraday mine, Bancroft district, Ontario, Canada
Field-hunting tip
Where it forms: In granite pegmatites and pegmatite veins cutting pyroxenite. If you start seeing calcite, apatite, diopside in float, you are in the right ground. Typical habit: metamict, pyramidal. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify tritomite-(y)?+
Where is tritomite-(y) found?+
Is tritomite-(y) safe to handle?+
What rocks look like tritomite-(y)?+
What minerals are found with tritomite-(y)?+
What kind of rock does tritomite-(y) form in?+
What is tritomite-(y) used for?+
Find tritomite-(y) on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
