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. Streak: white.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: light yellow.
- 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)Mn(Fe,Mn,Mg)₂(Al,Fe)₂(PO₄)₄(OH)₂·8H₂O
- 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
- A very rare mineral in phosphatic nodules in zoned granite pegmatite veins (Mangualde pegmatite, Portugal)
Where rockhounds find rittmannite
Classic worldwide localities
- Mangualde pegmatite, near Mesquitela, and the Bendada pegmatite, near Guarda, Portugal
Field-hunting tip
Where it forms: A very rare mineral in phosphatic nodules in zoned granite pegmatite veins (Mangualde pegmatite, Portugal). If you start seeing kryzhanovskite, frondelite, huréaulite in float, you are in the right ground. Typical habit: tabular crystals, massive, granular. 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?+
What minerals are found with rittmannite?+
What kind of rock does rittmannite form in?+
What is rittmannite used for?+
Find rittmannite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
