Ferhodsite is a rare member of the cobaltite group, characterized by its iron-dominant chemistry relative to cobalt. It is typically found as small, non-descript grains in cobalt-rich hydrothermal vein deposits. Due to its close physical resemblance to other sulfarsenides, positive identification usually requires advanced analysis like SEM-EDS or X-ray diffraction.
Is this ferhodsite?
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 ferhodsite with a known reference. Ferhodsite sits at Mohs 5-6 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Ferhodsite leaves a grey-black streak.
- 3Read the lusterHold the specimen under a strong light. Ferhodsite typically shows a metallic luster.
- 4Match the color rangeCompare against the expected color range: white, silver-white.
- 5Look at form & habitCrystal system: cubic. Typical habit: anhedral grains.
Often confused with
Ferhodsite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Ferhodsite leaves grey-black, Cobaltite leaves greyish-black.
How to tell apart: Streak differs — Ferhodsite leaves grey-black, Arsenopyrite leaves black.
How to tell apart: Streak differs — Ferhodsite leaves grey-black, Gersdorffite leaves grayish-black.
Often found alongside ferhodsite
Minerals reported to co-occur with ferhodsite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (Fe,Co)AsS
- Mohs hardness
- 5-6
- Density
- 6.57 g/cm³
- Colors
- Streak
- Grey-black
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Cubic
- Crystal habit
- Anhedral Grains
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Hydrothermal Veins
- Typical price
- $50-300 per specimen
Where rockhounds find ferhodsite
Classic worldwide localities
- Bou Azzer, Morocco
Field-hunting tip
Look in hydrothermal veins country — that is the host setting where ferhodsite typically forms. If you start seeing cobaltite, skutterudite, erythrite in float, you are in the right ground. Field specimens usually show a anhedral grains habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find ferhodsite on the map
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