Stetefeldtite is a rare silver-antimony oxide mineral typically found as a secondary oxidation product in silver-rich ore bodies. It usually appears as massive, earthy crusts or coatings in shades of brown to black, making identification difficult without laboratory analysis.
Is this stetefeldtite?
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 stetefeldtite with a known reference. Stetefeldtite sits at Mohs 3.5-4.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: pale yellow, shining.
- 3Read the lusterHold the specimen under a strong light. Luster: earthy.
- 4Match the color rangeCompare against the expected color range: brown, black, yellowish.
- 5Look at form & habitCrystal system: cubic. Typical habit: massive.
Often confused with
Stetefeldtite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Stibiconite is the harder of the two (Mohs 5.5-7 vs. 3.5-4.5); streak differs, so Stetefeldtite leaves pale yellow, shining, Stibiconite leaves light yellow; luster reads earthy on Stetefeldtite and pearly, opaline, glassy to earthy on Stibiconite.
How to tell apart: Streak differs, so Stetefeldtite leaves pale yellow, shining, Bindheimite leaves white, yellowish white; luster reads earthy on Stetefeldtite and resinous, dull, earthy on Bindheimite.
Often found alongside stetefeldtite
Minerals reported to co-occur with stetefeldtite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Ag₂Sb₂O₆(O,OH)
- Mohs hardness
- 3.5-4.5
- Density
- 4.6 g/cm³
- Streak
- Pale yellow, shining
- Luster
- Earthy
- Transparency
- Semitransparent
- Crystal system
- Cubic
- Crystal habit
- Massive
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Apparently an alteration product in the oxidized zone of some hydrothermal Ag–Sb-bearing mineral deposits, where it may constitute an ore of silver
Where rockhounds find stetefeldtite
Classic worldwide localities
- Belmont, Nye County, Montanta, USA (type locality)
Field-hunting tip
Where it forms: Apparently an alteration product in the oxidized zone of some hydrothermal Ag–Sb-bearing mineral deposits, where it may constitute an ore of silver. If you start seeing chalcocite, pyrite, quartz in float, you are in the right ground. Typical habit: massive. Train your eye for that shape before scanning the outcrop.
Common questions
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What rocks look like stetefeldtite?+
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Find stetefeldtite on the map
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