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.

Hardness

1.5-2

Mohs

Luster

Resinous

Streak

White

Transparency

Transparent

mineralrareSulfur family

Rosickýite

Hardness: 1.5-2
Luster: Resinous
Streak: White
Transparency: Transparent

Is this rosickýite?

5-step field check

Run through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.

1
Test the hardness
Try to scratch rosickýite with a known reference. Rosickýite sits at Mohs 1.5-2 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Rosickýite leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Rosickýite typically shows a resinous luster.
4
Match the color range
Compare against the expected color range: colorless, pale yellow.
5
Look at form & habit
Crystal system: monoclinic. Typical habit: microscopic crystals, crusts, coatings.

Often confused with

Rosickýite vs. its common look-alikes — and how to tell them apart in the field.

How to tell apart: Luster reads resinous on Rosickýite and vitreous on Gypsum.

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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: 1.5-2
Density: 2.07 g/cm³
Colors: Colorless Pale Yellow
Streak: White
Luster: Resinous
Transparency: Transparent
Crystal system: Monoclinic
Crystal habit: Microscopic Crystals, Crusts, Coatings
Cleavage: None Observed
Rarity: Rare
Uses: Collector
Host rock: Fumaroles, Volcanic Vents
Typical price: $50-200 for micro-mount specimens

Where rockhounds find rosickýite

Classic worldwide localities

Czech Republic
Italy
USA

Field-hunting tip

Look in fumaroles, volcanic vents country — that is the host setting where rosickýite typically forms. If you start seeing sulfur, gypsum, aragonite in float, you are in the right ground. Field specimens usually show a microscopic crystals, crusts, coatings habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify rosickýite?+

Mohs hardness is 1.5-2. It typically shows a resinous luster. The streak is white. Common colors include colorless, pale yellow.

Where is rosickýite found?+

Notable localities include Czech Republic; Italy; USA.

How much is rosickýite worth?+

Typical asking prices fall in the range of $50-200 for micro-mount specimens. Quality, size, and provenance can move individual specimens well outside that range.

What rocks look like rosickýite?+

Rosickýite is most often confused with Sulfur, Gypsum. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with rosickýite?+

Rosickýite commonly co-occurs with Sulfur, Gypsum, Aragonite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does rosickýite form in?+

Rosickýite typically forms in fumaroles, volcanic vents. Working float back to the host body is the standard way to chase a fresh occurrence.

What is rosickýite used for?+

Rosickýite is used in collector.

Find rosickýite on the map

RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.