Rosickýite is a rare polymorph of native sulfur that forms as microscopic crystals or delicate coatings in volcanic environments. It is notoriously unstable and difficult to preserve, often reverting to ordinary orthorhombic sulfur if not kept in controlled conditions.
Is this rosickýite?
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 rosickýite with a known reference. Rosickýite sits at Mohs 2-3, 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: adamantine.
- 4Match the color rangeCompare against the expected color range: colorless, light yellow.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: microscopic crystals.
Often confused with
Rosickýite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside rosickýite
Minerals reported to co-occur with rosickýite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- S
- Mohs hardness
- 2-3
- Density
- 2.072-2.073 g/cm³
- Colors
- Streak
- White
- Luster
- Adamantine
- Transparency
- Transparent to translucent
- Crystal system
- Monoclinic
- Crystal habit
- Microscopic crystals
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In hollow “limonite” nodules in a thin clay stratum (Havírna, Czech Republic); in fumaroles (Vulcano, Italy); an alteration product of pyrite-rich asphalt (La Presta mine, Switzerland)
Where rockhounds find rosickýite
Classic worldwide localities
- Point Rincon, Ventura Co., and in the salt pan of Death Valley, California, USA
- Havírna, near Letovice (type locality), and at Visky, Czech Republic
- La Presta asphalt mine, near Travers, Neuchâtel, Switzerland
- St. Andreasberg, Harz Mountains, and at Ronneburg, Thuringia, Germany
- Vulcano, Lipari Islands, Italy
Field-hunting tip
Where it forms: In hollow “limonite” nodules in a thin clay stratum (Havírna, Czech Republic); in fumaroles (Vulcano, Italy); an alteration product of pyrite-rich asphalt (La Presta mine, Switzerland). If you start seeing pyrite, gypsum, rozenite in float, you are in the right ground. Typical habit: microscopic crystals. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify rosickýite?+
Where is rosickýite found?+
What rocks look like rosickýite?+
What minerals are found with rosickýite?+
What kind of rock does rosickýite form in?+
What is rosickýite used for?+
Find rosickýite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
