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 3.5-4, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Bendadaite leaves a greenish yellow streak.
- 3Read the lusterHold the specimen under a strong light. Bendadaite typically shows a vitreous to adamantine luster.
- 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.
How to tell apart: Streak differs, so Bendadaite leaves greenish yellow, Dufrénite leaves light green; luster reads vitreous to adamantine on Bendadaite and vitreous on Dufrénite.
How to tell apart: Streak differs, so Bendadaite leaves greenish yellow, Rockbridgeite leaves greenish-brown; luster reads vitreous to adamantine on Bendadaite and vitreous on Rockbridgeite.
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
- 3.5-4
- Density
- 3.15 g/cm³
- Streak
- Greenish Yellow
- Luster
- Vitreous to Adamantine
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Fibrous Aggregates, Radial Sprays, Spherical Clusters
- Cleavage
- Good On {010}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Granite Pegmatites
Where rockhounds find bendadaite
Classic worldwide localities
- Bendada, Portugal
- Hagendorf-Pleystein, Germany
- Linopolis, Brazil
Field-hunting tip
Look in granite pegmatites country, the host setting where bendadaite typically forms. If you start seeing triphylite, vivianite, quartz in float, you are in the right ground. Field specimens usually show a fibrous aggregates, radial sprays, spherical clusters habit, so 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?+
What kind of rock does bendadaite form in?+
What is bendadaite used for?+
Find bendadaite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
