Phosphosiderite is a rare phosphate mineral prized by collectors for its vivid magenta to violet color. It is most commonly found in massive or nodular habits and is often polished for cabochons due to its attractive, soft appearance.
Is this phosphosiderite?
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 phosphosiderite with a known reference. Phosphosiderite sits at Mohs 3.5-4, 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: pink, colorless, purple, red, red violet.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: encrustations, spherical.
Often confused with
Phosphosiderite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside phosphosiderite
Minerals reported to co-occur with phosphosiderite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- FePO₄·2H₂O
- Mohs hardness
- 3.5-4
- Density
- 2.74-2.76 g/cm³
- Streak
- White
- Luster
- Vitreous to subresinous
- Transparency
- Transparent to translucent
- Crystal system
- Monoclinic
- Crystal habit
- Encrustations, spherical
- Cleavage
- {010}, good; {001}, indistinct
- Rarity
- Uncommon
- Uses
- Collector, Lapidary
- Host rock
- Typically an alteration product of triphylite in zoned complex granite pegmatites; may be a component of soils; replacing bones or shells
Where rockhounds find phosphosiderite
Classic worldwide localities
- Palermo #1 and Fletcher mines, near North Groton, Grafton Co., New Hampshire, USA
- Mullica Hill, Gloucester Co., New Jersey, USA
- Bethel Church, Pike Co., Indiana, USA
- Williams pegmatites, about eight km south of Rockford, Coosa Co., Alabama, USA
- Kalterborn mine, near Eiserfeld, North Rhine-Westphalia, Germany
- Kreuzberg, Pleystein, Germany
Field-hunting tip
Where it forms: Typically an alteration product of triphylite in zoned complex granite pegmatites; may be a component of soils; replacing bones or shells. If you start seeing triphylite, barbosalite, leucophosphite in float, you are in the right ground. Typical habit: encrustations, spherical. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify phosphosiderite?+
Where is phosphosiderite found?+
What rocks look like phosphosiderite?+
What minerals are found with phosphosiderite?+
What kind of rock does phosphosiderite form in?+
What is phosphosiderite used for?+
Find phosphosiderite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
