Redondite is a variety of variscite that contains significant iron substituting for aluminum. It typically occurs as soft, earthy, or nodular masses in phosphate-rich environments, most notably found on the island of Redonda. Collectors often value it for its association with secondary phosphate mineral assemblages.
Is this redondite?
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 redondite with a known reference. Redondite sits at Mohs 3.5-4.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Redondite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Redondite typically shows a dull luster.
- 4Match the color rangeCompare against the expected color range: yellow, green, white.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: massive, crusts, or nodular aggregates.
Often confused with
Redondite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Luster reads dull on Redondite and waxy on Variscite.
How to tell apart: Luster reads dull on Redondite and vitreous on Strengite.
How to tell apart: Luster reads dull on Redondite and vitreous on Crandallite.
Often found alongside redondite
Minerals reported to co-occur with redondite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (Al,Fe)PO₄·2H₂O
- Mohs hardness
- 3.5-4.5
- Density
- 2.5-2.6 g/cm³
- Streak
- White
- Luster
- Dull
- Transparency
- Opaque
- Crystal system
- Orthorhombic
- Crystal habit
- Massive, Crusts, Or Nodular Aggregates
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector, Lapidary
- Host rock
- Phosphate Rock Deposits
- Typical price
- $10-50 per specimen
Where rockhounds find redondite
Classic worldwide localities
- Redonda
- Leeward Islands
Field-hunting tip
Look in phosphate rock deposits country, the host setting where redondite typically forms. If you start seeing crandallite, variscite, strengite in float, you are in the right ground. Field specimens usually show a massive, crusts, or nodular aggregates habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify redondite?+
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Find redondite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
