Hellandite-(Ce) is a rare borosilicate mineral typically found in complex granite pegmatites. It usually forms as brown to reddish-brown prismatic crystals and is highly valued by collectors due to its association with radioactive rare earth minerals.
Is this hellandite-(ce)?
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 hellandite-(ce) with a known reference. Hellandite-(Ce) sits at Mohs 5.5-6, 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 green, pale brown.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: euhedral crystals, microscopic crystals.
Often confused with
Hellandite-(Ce) vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Hellandite-(Ce) leaves white, Allanite leaves gray; luster reads vitreous to dull on Hellandite-(Ce) and submetallic on Allanite.
How to tell apart: Streak differs, so Hellandite-(Ce) leaves white, Gadolinite-(Y) leaves greenish gray.
Often found alongside hellandite-(ce)
Minerals reported to co-occur with hellandite-(ce). Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (Ca,REE)₄Ce₂Al□₂(B₄Si₄O₂₂)(OH)₂
- Mohs hardness
- 5.5-6
- Density
- 3.73 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous to dull
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Euhedral crystals, microscopic crystals
- Cleavage
- Poor on {100}, {010}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Inside miarolitic cavities in alkali-syenite volcanic ejecta in an ignimbrite
Where rockhounds find hellandite-(ce)
Classic worldwide localities
- Near Capranica, Vico volcanic province, Latium, Italy
Field-hunting tip
Where it forms: Inside miarolitic cavities in alkali-syenite volcanic ejecta in an ignimbrite. If you start seeing vonsenite, helvite, baddeleyite in float, you are in the right ground. Typical habit: euhedral crystals, microscopic crystals. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify hellandite-(ce)?+
Where is hellandite-(ce) found?+
Is hellandite-(ce) safe to handle?+
What rocks look like hellandite-(ce)?+
What minerals are found with hellandite-(ce)?+
What kind of rock does hellandite-(ce) form in?+
What is hellandite-(ce) used for?+
Find hellandite-(ce) on the map
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