Bendadaite is a rare iron arsenate, typically blackish green to dark brownish. It is associated with scorodite-mansfieldite and gypsum. It was first described from the dumps of the pegmatite at Bendada, near Guarda, province Beira Alta, central Portugal.
Is this bendadaite?
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 bendadaite with a known reference. Bendadaite sits at Mohs ~3, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: greenish yellow.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous to sub-adamantine.
- 4Match the color rangeCompare against the expected color range: blackish green, dark brownish.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: fibrous aggregates, radial sprays, spherical clusters.
Often confused with
Bendadaite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside bendadaite
Minerals reported to co-occur with bendadaite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Fe²⁺Fe³⁺₂(AsO₄)₂(OH)₂·4H₂O
- Mohs hardness
- ~3
- Density
- 3.15 g/cm³
- Colors
- Blackish greenDark brownish
- Streak
- Greenish yellow
- Luster
- Vitreous to sub-adamantine
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Fibrous aggregates, radial sprays, spherical clusters
- Cleavage
- Good on {010}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- From the dumps of phosphate-bearing columbite-beryl pegmatite; a secondary (or late-hydrothermal) mineral with Fe and As derived from weathered arsenopyrite
Where rockhounds find bendadaite
Classic worldwide localities
- Dumps of the pegmatite at Bendada, near Guarda, province Beira Alta, central Portugal (type locality)
- Granite pegmatite of Almerindo mine, Linópolis, Divino das Laranjeiras county, Minas Gerais, Brazil (type locality)
- Veta Negra mine, Copiapó province, Chile, Italy
- Oumlil-East, Bou Azzer district, Morocco, Italy
- Pira Inferida yard, Fenugu Sibiri mine, Gonnosfanadiga, Medio Campidano Province, Sardinia, Italy
Field-hunting tip
Where it forms: From the dumps of phosphate-bearing columbite-beryl pegmatite; a secondary (or late-hydrothermal) mineral with Fe and As derived from weathered arsenopyrite. If you start seeing scorodite-mansfieldite, gypsum, albite in float, you are in the right ground. Typical habit: fibrous aggregates, radial sprays, spherical clusters. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify bendadaite?+
Where is bendadaite found?+
Is bendadaite safe to handle?+
What rocks look like bendadaite?+
What minerals are found with bendadaite?+
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Find bendadaite on the map
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