Stoiberite is an extremely rare copper vanadate mineral first discovered in the fumaroles of the Izalco Volcano. Collectors typically find it as microscopic, dark red tabular crystals forming thin encrustations on volcanic substrates.
Is this stoiberite?
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 stoiberite with a known reference. Stoiberite sits at Mohs 3 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Stoiberite leaves a orange-red streak.
- 3Read the lusterHold the specimen under a strong light. Stoiberite typically shows a adamantine luster.
- 4Match the color rangeCompare against the expected color range: dark red, orange-red.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: tabular to blocky crystals, often as crusts.
Often confused with
Stoiberite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Stoiberite leaves orange-red, Ziesite leaves yellow; luster reads adamantine on Stoiberite and vitreous on Ziesite.
How to tell apart: Streak differs — Stoiberite leaves orange-red, Blossite leaves black; luster reads adamantine on Stoiberite and submetallic on Blossite.
Often found alongside stoiberite
Minerals reported to co-occur with stoiberite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Cu₅V₂O₁₀
- Mohs hardness
- 3
- Density
- 5.68 g/cm³
- Colors
- Streak
- Orange-red
- Luster
- Adamantine
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Tabular to Blocky Crystals, Often as Crusts
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Fumarolic Encrustations On Volcanic Rocks
- Typical price
- $50-500+ depending on crystal size and quality
Where rockhounds find stoiberite
Classic worldwide localities
- Izalco Volcano, El Salvador
Field-hunting tip
Look in fumarolic encrustations on volcanic rocks country — that is the host setting where stoiberite typically forms. If you start seeing ziesite, thenardite, sylvite in float, you are in the right ground. Field specimens usually show a tabular to blocky crystals, often as crusts habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find stoiberite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
