Senarmontite is an antimony oxide mineral typically found in the oxidation zones of antimony deposits. It is most commonly identified by its sharp octahedral crystals and high density, often altering to the orthorhombic polymorph valentinite.
Is this senarmontite?
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 senarmontite with a known reference. Senarmontite sits at Mohs 2-2.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: white.
- 3Read the lusterHold the specimen under a strong light. Luster: resinous to subadamantine.
- 4Match the color rangeCompare against the expected color range: white, colorless, gray.
- 5Look at form & habitCrystal system: cubic. Typical habit: encrustations, euhedral crystals, massive.
Often confused with
Senarmontite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Luster reads resinous to subadamantine on Senarmontite and adamantine, pearly on cleavages on Valentinite.
How to tell apart: Luster reads resinous to subadamantine on Senarmontite and vitreous to silky on Arsenolite.
Often found alongside senarmontite
Minerals reported to co-occur with senarmontite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Sb₂O₃
- Mohs hardness
- 2-2.5
- Density
- 5.50 g/cm³
- Streak
- White
- Luster
- Resinous to subadamantine
- Transparency
- Transparent to translucent
- Crystal system
- Cubic
- Crystal habit
- Encrustations, euhedral crystals, massive
- Cleavage
- {111}, interrupted
- Rarity
- Uncommon
- Uses
- Collector, Minor ore of antimony
- Host rock
- Formed by oxidation of antimony, stibnite, and other antimony minerals in hydrothermal antimony-bearing deposits
Where rockhounds find senarmontite
Classic worldwide localities
- Green prospect, Mopung Hills, Churchill Co., Nevada, USA
- Sensa (Haminate mine), Aı̈n-el-Bebbouch, Qacentina (Constantine), Algeria
- Globe and Phoenix mine, Kwekwe (Que Que), Zimbabwe
- Pernek, near Pezinok, and Dubrava, Slovakia
- Arnsberg, Westphalia, and St. Ulrich, Black Forest, Germany
- Anzat-le-Luguet, Puy-de-Dôme, France
Field-hunting tip
Where it forms: Formed by oxidation of antimony, stibnite, and other antimony minerals in hydrothermal antimony-bearing deposits. If you start seeing valentinite, kermesite, stibiconite in float, you are in the right ground. Typical habit: encrustations, euhedral crystals, massive. Train your eye for that shape before scanning the outcrop.
Common questions
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Find senarmontite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
