Reddingite is a rare phosphate mineral typically found in phosphate-rich zones of granite pegmatites. It forms short, blocky, prismatic crystals or compact granular masses that are prized by advanced collectors of phosphate minerals.
Is this reddingite?
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 reddingite with a known reference. Reddingite sits at Mohs 3-3.5, 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 subresinous.
- 4Match the color rangeCompare against the expected color range: white, yellowish white, colorless, reddish brown, dark brown.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: crystalline, granular.
Often confused with
Reddingite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside reddingite
Minerals reported to co-occur with reddingite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Mn²⁺₃(PO₄)₂·3H₂O
- Mohs hardness
- 3-3.5
- Density
- 3.10-3.24 g/cm³
- Streak
- White
- Luster
- Vitreous to subresinous
- Transparency
- Transparent to translucent
- Crystal system
- Orthorhombic
- Crystal habit
- Crystalline, granular
- Cleavage
- On {010}, poor
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A rare secondary hydrothermal alteration product in zoned complex granite pegmatites
Where rockhounds find reddingite
Classic worldwide localities
- Branchville, in the town of Redding, Fairfield Co., Connecticut (type locality)
Field-hunting tip
Where it forms: A rare secondary hydrothermal alteration product in zoned complex granite pegmatites. If you start seeing dickinsonite, triploidite, triplite in float, you are in the right ground. Typical habit: crystalline, granular. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify reddingite?+
Where is reddingite found?+
What rocks look like reddingite?+
What minerals are found with reddingite?+
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What is reddingite used for?+
Find reddingite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
