Jurbanite is a rare aluminum sulfate mineral typically found as a secondary precipitate in volcanic fumarole environments. Collectors usually identify it by its delicate, prismatic, or acicular crystal habit and its occurrence in arid, sulfate-rich volcanic areas.
Is this jurbanite?
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 jurbanite with a known reference. Jurbanite sits at Mohs ~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: vitreous.
- 4Match the color rangeCompare against the expected color range: colorless.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: prismatic crystals, radial aggregates, crusts.
Often confused with
Jurbanite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside jurbanite
Minerals reported to co-occur with jurbanite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Al(SO₄)(OH)·5H₂O
- Mohs hardness
- ~2.5
- Density
- 1.786 g/cm³
- Colors
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Prismatic crystals, radial aggregates, crusts
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- As rare secondary crusts in humid tunnels in oxidized portions of sulfide deposits in aluminous rocks; apparently deposited directly from mine water at about 27°C and 100% humidity (San Manuel mine, Arizona, USA)
Where rockhounds find jurbanite
Classic worldwide localities
- San Manuel mine, Mammoth district, Pinal Co., Arizona, USA
- Cetine mine, 20 km southwest of Siena, Tuscany, Italy
Field-hunting tip
Where it forms: As rare secondary crusts in humid tunnels in oxidized portions of sulfide deposits in aluminous rocks; apparently deposited directly from mine water at about 27°C and 100% humidity (San Manuel mine, Arizona, USA). If you start seeing epsomite, hexahydrite, pickeringite in float, you are in the right ground. Typical habit: prismatic crystals, radial aggregates, crusts. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify jurbanite?+
Where is jurbanite found?+
What rocks look like jurbanite?+
What minerals are found with jurbanite?+
What kind of rock does jurbanite form in?+
What is jurbanite used for?+
Find jurbanite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
