Ferrokësterite is a rare member of the stannite group that occurs primarily as small, opaque black grains within tin-bearing ore deposits. It is chemically similar to kësterite but with iron substituting for zinc in the crystal structure, often making identification difficult without specialized chemical analysis like EDS.
Is this ferrokësterite?
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 ferrokësterite with a known reference. Ferrokësterite 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. Ferrokësterite leaves a black streak.
- 3Read the lusterHold the specimen under a strong light. Ferrokësterite typically shows a metallic luster.
- 4Match the color rangeCompare against the expected color range: black, brownish-black.
- 5Look at form & habitCrystal system: tetragonal. Typical habit: anhedral grains, massive, granular.
Often confused with
Ferrokësterite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside ferrokësterite
Minerals reported to co-occur with ferrokësterite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Cu₂FeSnS₄
- Mohs hardness
- 3.5
- Density
- 4.56 g/cm³
- Colors
- Streak
- Black
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Tetragonal
- Crystal habit
- Anhedral Grains, Massive, Granular
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Hydrothermal Tin-bearing Veins
- Typical price
- $20-150 thumbnail
Where rockhounds find ferrokësterite
Classic worldwide localities
- Kester, Sakha Republic, Russia
- Tasna, Bolivia
- Renison Bell, Tasmania, Australia
- Yaogangxian, China
Field-hunting tip
Look in hydrothermal tin-bearing veins country — that is the host setting where ferrokësterite typically forms. If you start seeing cassiterite, chalcopyrite, arsenopyrite in float, you are in the right ground. Field specimens usually show a anhedral grains, massive, granular habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify ferrokësterite?+
Where is ferrokësterite found?+
How much is ferrokësterite worth?+
Is ferrokësterite safe to handle?+
What rocks look like ferrokësterite?+
What minerals are found with ferrokësterite?+
What kind of rock does ferrokësterite form in?+
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Find ferrokësterite on the map
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