Rittmannite is a rare phosphate mineral found primarily in granite pegmatites as a late-stage alteration product. It typically forms tabular crystals or granular masses with a distinct yellowish to reddish-brown coloration. Collectors generally find it as an accessory mineral in well-studied phosphate-bearing pegmatite deposits.
Is this rittmannite?
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 rittmannite with a known reference. Rittmannite sits at Mohs 4.5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Rittmannite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Rittmannite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: yellow, brown, reddish-brown.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: tabular crystals, massive, granular.
Often confused with
Rittmannite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside rittmannite
Minerals reported to co-occur with rittmannite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (Mn,Ca,Fe)₅(PO₄)₄(OH)₂
- Mohs hardness
- 4.5
- Density
- 3.55 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Tabular Crystals, Massive, Granular
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Granite Pegmatites
- Typical price
- $20-100 per specimen
Where rockhounds find rittmannite
Classic worldwide localities
- Hagendorf, Germany
- Tip Top Mine, South Dakota, USA
- White Elephant Mine, South Dakota, USA
Field-hunting tip
Look in granite pegmatites country — that is the host setting where rittmannite typically forms. If you start seeing triphylite, apatite, siderite in float, you are in the right ground. Field specimens usually show a tabular crystals, massive, granular habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find rittmannite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
