Benauite is a rare strontium-iron phosphate member of the crandallite group typically found as small, thin tabular crystals or as crusts on iron-rich matrices. It is a secondary mineral primarily identified through chemical analysis or XRD due to its superficial resemblance to other phosphate group members. It is highly sought after by mineral collectors specializing in rare phosphates and species from type localities.
Is this benauite?
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 benauite with a known reference. Benauite 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: yellowish.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous to resinous.
- 4Match the color rangeCompare against the expected color range: yellow, brown.
- 5Look at form & habitCrystal system: trigonal. Typical habit: aggregates, radial.
Often confused with
Benauite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Crandallite is the harder of the two (Mohs 5 vs. ~3.5); streak differs, so Benauite leaves yellowish, Crandallite leaves white.
How to tell apart: Gorceixite is the harder of the two (Mohs 6 vs. ~3.5); streak differs, so Benauite leaves yellowish, Gorceixite leaves white.
How to tell apart: Plumbogummite is the harder of the two (Mohs 4.5-5 vs. ~3.5); streak differs, so Benauite leaves yellowish, Plumbogummite leaves white.
Often found alongside benauite
Minerals reported to co-occur with benauite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- SrFe₃(PO₄)₂(OH)₅·H₂O
- Mohs hardness
- ~3.5
- Density
- 3.65 g/cm³
- Streak
- Yellowish
- Luster
- Vitreous to resinous
- Transparency
- Transparent to translucent
- Crystal system
- Trigonal
- Crystal habit
- Aggregates, radial
- Cleavage
- On {0001}, perfect
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A secondary mineral in the oxidized zone of a hydrothermal polymetallic barite–fluorite deposit
Where rockhounds find benauite
Classic worldwide localities
- Clara mine, near Oberwolfach, Black Forest, Germany
Field-hunting tip
Where it forms: A secondary mineral in the oxidized zone of a hydrothermal polymetallic barite–fluorite deposit. If you start seeing kidwellite, fluorite, goethite in float, you are in the right ground. Typical habit: aggregates, radial. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify benauite?+
Where is benauite found?+
What rocks look like benauite?+
What minerals are found with benauite?+
What kind of rock does benauite form in?+
What is benauite used for?+
Find benauite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
