Perloffite is a rare phosphate mineral primarily found in complex granite pegmatites. It typically appears as dark brown, tabular, or blocky crystals and is highly sought after by advanced systematic mineral collectors.
Is this perloffite?
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 perloffite with a known reference. Perloffite sits at Mohs 4 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Perloffite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Perloffite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: dark brown, reddish brown.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: tabular to blocky crystals, often as crusts or granular aggregates.
Often confused with
Perloffite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside perloffite
Minerals reported to co-occur with perloffite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- BaMn²⁺₂Fe³⁺₂(PO₄)₃(OH)₃
- Mohs hardness
- 4
- Density
- 3.84 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Tabular to Blocky Crystals, Often as Crusts or Granular Aggregates
- Cleavage
- None Observed
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Granite Pegmatites
- Typical price
- $50-300 per thumbnail or small specimen
Where rockhounds find perloffite
Classic worldwide localities
- Tip Top mine, Custer, South Dakota, USA
- Big Chief mine, Keystone, South Dakota, USA
- Mangualde, Portugal
Field-hunting tip
Look in granite pegmatites country — that is the host setting where perloffite typically forms. If you start seeing triphylite, apatite, rockbridgeite in float, you are in the right ground. Field specimens usually show a tabular to blocky crystals, often as crusts or granular aggregates habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find perloffite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
