Perrierite-(La) is a rare silicate mineral belonging to the chevkinite group, often appearing as dark, lustrous, tabular crystals. It is typically found in alkaline volcanic rocks or pegmatites and is notable for its weak radioactive properties due to rare earth element content.
Is this perrierite-(la)?
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 perrierite-(la) with a known reference. Perrierite-(La) sits at Mohs 6, 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: vitreous.
- 4Match the color rangeCompare against the expected color range: black.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: prismatic, tabular, or granular.
Often confused with
Perrierite-(La) vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Perrierite-(La) leaves brown, Allanite leaves gray; luster reads vitreous on Perrierite-(La) and submetallic on Allanite.
How to tell apart: Streak differs, so Perrierite-(La) leaves brown, Zirkelite leaves brownish gray; luster reads vitreous on Perrierite-(La) and resinous on Zirkelite.
Often found alongside perrierite-(la)
Minerals reported to co-occur with perrierite-(la). Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (La,Ce,Ca)₄(Fe,Mn)(Ti,Fe,Al)₄(Si₂O₇)₂O₈
- Mohs hardness
- 6
- Density
- 4.791 g/cm³
- Colors
- Streak
- Brown
- Luster
- Vitreous
- Transparency
- Translucent to nearly opaque
- Crystal system
- Monoclinic
- Crystal habit
- Prismatic, tabular, or granular
- Cleavage
- Distinct on (001)
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In miarolitic cavities in sanidinite lava rock, probably pneumatolytic
Where rockhounds find perrierite-(la)
Classic worldwide localities
- Dellen quarry, near Mendig, Laacher See region, Eifel Mts., Rhineland-Palatinate (Rheinland-Pfalz), Germany
Field-hunting tip
Where it forms: In miarolitic cavities in sanidinite lava rock, probably pneumatolytic. If you start seeing sanidine, phlogopite, pyrophanite in float, you are in the right ground. Typical habit: prismatic, tabular, or granular. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify perrierite-(la)?+
Where is perrierite-(la) found?+
Is perrierite-(la) safe to handle?+
What rocks look like perrierite-(la)?+
What minerals are found with perrierite-(la)?+
What kind of rock does perrierite-(la) form in?+
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Find perrierite-(la) on the map
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