Bergslagite is an exceptionally rare calcium beryllium arsenate mineral known primarily from the Langban iron-manganese mine in Sweden. It typically forms colorless to pale yellow tabular crystals and is frequently sought after by advanced systematic collectors for its unique chemistry and scarcity.
Is this bergslagite?
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 bergslagite with a known reference. Bergslagite sits at Mohs 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 to greasy.
- 4Match the color rangeCompare against the expected color range: colorless, gray, gray white, white.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: tabular crystals, subparallel aggregates.
Often confused with
Bergslagite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside bergslagite
Minerals reported to co-occur with bergslagite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CaBeAsO₄(OH)
- Mohs hardness
- 5
- Density
- 3.40 g/cm³
- Streak
- White
- Luster
- Vitreous to greasy
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Tabular crystals, subparallel aggregates
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In thin veins in pieces of hematite ore found on mine dumps from a metamorphosed Fe–Mn orebody (Långban, Sweden); in rhyolite (Sailauf, Germany)
Where rockhounds find bergslagite
Classic worldwide localities
- Långban, Värmland, Sweden
- Falotta mine, Oberhalbstein, and in the Fianel mine, Val Ferrera, Graubünden, Switzerland
- Sailauf, northeast of Aschaffenburg, Spessart Mountains, Bavaria, Germany
Field-hunting tip
Where it forms: In thin veins in pieces of hematite ore found on mine dumps from a metamorphosed Fe–Mn orebody (Långban, Sweden); in rhyolite (Sailauf, Germany). If you start seeing manganoan diopside, manganberzeliite, tilasite in float, you are in the right ground. Typical habit: tabular crystals, subparallel aggregates. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify bergslagite?+
Where is bergslagite found?+
Is bergslagite safe to handle?+
What rocks look like bergslagite?+
What minerals are found with bergslagite?+
What kind of rock does bergslagite form in?+
What is bergslagite used for?+
Find bergslagite on the map
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