Serrabrancaite is a rare manganese phosphate mineral found in phosphate-rich pegmatites. It typically occurs as small, pale, tabular crystals or crusts and is identified by its association with secondary phosphate minerals in the Brazilian localities where it was first discovered.
Is this serrabrancaite?
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 serrabrancaite with a known reference. Serrabrancaite 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: olive-green.
- 3Read the lusterHold the specimen under a strong light. Luster: adamantine.
- 4Match the color rangeCompare against the expected color range: dark brown, dark greenish black.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: microscopic crystals, pseudo cubic.
Often confused with
Serrabrancaite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Serrabrancaite leaves olive-green, Heterosite leaves pale purple; luster reads adamantine on Serrabrancaite and satiny on fresh surfaces, dull to earthy on Heterosite.
How to tell apart: Streak differs, so Serrabrancaite leaves olive-green, Triphylite leaves white to grayish white; luster reads adamantine on Serrabrancaite and vitreous to subresinous on Triphylite.
Often found alongside serrabrancaite
Minerals reported to co-occur with serrabrancaite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- MnPO₄·H₂O
- Mohs hardness
- 3.5
- Density
- 3.17 g/cm³
- Colors
- Dark brownDark greenish black
- Streak
- Olive-green
- Luster
- Adamantine
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Microscopic crystals, pseudo cubic
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A secondary alteration product of triplite in a granitic pegmatite
Where rockhounds find serrabrancaite
Classic worldwide localities
- Alto Serra Branca granitic pegmatite, ~10 km southwest of the village Pedra Lavrada, Paraiba State, Brazil
Field-hunting tip
Where it forms: A secondary alteration product of triplite in a granitic pegmatite. If you start seeing vernadite, phosphosiderite in float, you are in the right ground. Typical habit: microscopic crystals, pseudo cubic. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify serrabrancaite?+
Where is serrabrancaite found?+
What rocks look like serrabrancaite?+
What minerals are found with serrabrancaite?+
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Find serrabrancaite on the map
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