Richellite is an uncommon phosphate mineral that typically occurs as compact crusts or reniform masses. It is primarily identified by its characteristic yellowish color and association with other phosphate minerals in sedimentary occurrences.
Is this richellite?
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 richellite with a known reference. Richellite sits at Mohs 2-3, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: reddish to yellowish brown.
- 3Read the lusterHold the specimen under a strong light. Luster: greasy to hornlike, subvitreous.
- 4Match the color rangeCompare against the expected color range: yellow brown, reddish brown.
- 5Look at form & habitCrystal system: tetragonal. Typical habit: massive.
Often confused with
Richellite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Richellite leaves reddish to yellowish brown, Dufrénite leaves green; luster reads greasy to hornlike, subvitreous on Richellite and vitreous to silky on Dufrénite.
How to tell apart: Streak differs, so Richellite leaves reddish to yellowish brown, Rockbridgeite leaves greenish gray; luster reads greasy to hornlike, subvitreous on Richellite and vitreous to dull on Rockbridgeite.
Often found alongside richellite
Minerals reported to co-occur with richellite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CaFe₂(PO₄)₂(OH,F)₂
- Mohs hardness
- 2-3
- Density
- 2 g/cm³
- Streak
- Reddish to yellowish brown
- Luster
- Greasy to hornlike, subvitreous
- Transparency
- Semitransparent
- Crystal system
- Tetragonal
- Crystal habit
- Massive
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Presumably as a secondary mineral in phosphatic sedimentary rocks
Where rockhounds find richellite
Classic worldwide localities
- Gold Quarry mine, near Carlin, Maggie Creek district, Eureka Co., Nevada, USA
- Richelle, near Visé, Belgium
Field-hunting tip
Where it forms: Presumably as a secondary mineral in phosphatic sedimentary rocks. If you start seeing halloysite, allophane, koninckite in float, you are in the right ground. Typical habit: massive. Train your eye for that shape before scanning the outcrop.
Common questions
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Find richellite on the map
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