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 3.5, 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
- 3.5
- Density
- 2.81 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Tabular Crystals, Massive, Granular
- Cleavage
- On {001}, Indistinct
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Granite Pegmatites
Where rockhounds find rittmannite
Classic worldwide localities
- Mangualde pegmatite, and the Bendada pegmatite, near Guarda, Portugal
Field-hunting tip
Look in granite pegmatites country, 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
How do you identify rittmannite?+
Where is rittmannite found?+
What rocks look like rittmannite?+
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Find rittmannite on the map
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