Coquandite is a rare secondary antimony sulfate mineral typically found as small, brilliant, yellow to colorless tabular crystals. It most commonly occurs in oxidized zones of antimony-rich hydrothermal deposits, often associated with other antimony oxides. Collectors prize it for its high luster and complex crystal habits, though it is usually found only as small specimens.
Is this coquandite?
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 coquandite with a known reference. Coquandite sits at Mohs 2 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Coquandite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Coquandite typically shows a adamantine luster.
- 4Match the color rangeCompare against the expected color range: yellow, orange, colorless.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: tabular crystals, subparallel aggregates, crusts.
Often confused with
Coquandite vs. its common look-alikes — and how to tell them apart in the field.
Often found alongside coquandite
Minerals reported to co-occur with coquandite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Sb₆O₈(SO₄)
- Mohs hardness
- 2
- Density
- 5.45 g/cm³
- Streak
- White
- Luster
- Adamantine
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Tabular Crystals, Subparallel Aggregates, Crusts
- Cleavage
- Perfect
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Hydrothermal Veins in Antimony-bearing Deposits
- Typical price
- $50-300 per thumbnail specimen
Where rockhounds find coquandite
Classic worldwide localities
- Cetine mine, Tuscany, Italy
- Pereta mine, Tuscany, Italy
Field-hunting tip
Look in hydrothermal veins in antimony-bearing deposits country — that is the host setting where coquandite typically forms. If you start seeing stibnite, valentinite, senarmontite in float, you are in the right ground. Field specimens usually show a tabular crystals, subparallel aggregates, crusts habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find coquandite on the map
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