Brandtite is a rare hydrated calcium manganese arsenate mineral that typically forms as small, clear to white crystals in manganese-rich metamorphic environments. It is most frequently collected from the famous Langban mines in Sweden or the Franklin/Sterling Hill districts in New Jersey, where it is often associated with other rare arsenate species. Due to its arsenic content, it should be stored in a sealed container and handled with caution.
Is this brandtite?
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 brandtite with a known reference. Brandtite sits at Mohs 3-4, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Brandtite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Brandtite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: white, colorless, pale yellow, pale pink.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: prismatic to tabular crystals, sometimes crusts or radial aggregates.
Often confused with
Brandtite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside brandtite
Minerals reported to co-occur with brandtite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Ca₂Mn(AsO₄)₂·2H₂O
- Mohs hardness
- 3-4
- Density
- 3.37 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Prismatic to Tabular Crystals, Sometimes Crusts or Radial Aggregates
- Cleavage
- Distinct On {010}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Metamorphosed Manganese Ore Deposits
- Typical price
- $20-150 for thumbnail to small cabinet specimens
Where rockhounds find brandtite
Classic worldwide localities
- Langban, Sweden
- Franklin, New Jersey, USA
- Sterling Hill, New Jersey, USA
- Jakobsberg, Sweden
Field-hunting tip
Look in metamorphosed manganese ore deposits country, the host setting where brandtite typically forms. If you start seeing hausmannite, barite, calcite in float, you are in the right ground. Field specimens usually show a prismatic to tabular crystals, sometimes crusts or radial aggregates habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify brandtite?+
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Find brandtite on the map
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