Mathesiusite is a rare secondary uranium sulfate mineral discovered in the historic mining district of Jáchymov. It typically forms thin, bright yellow platy crystals coating other uranium minerals in oxidized hydrothermal zones. Due to its radioactive nature and extreme rarity, it is highly sought after by advanced systematic mineral collectors.
Is this mathesiusite?
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 mathesiusite with a known reference. Mathesiusite 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. Streak: greenish white.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: yellowish green.
- 5Look at form & habitCrystal system: tetragonal. Typical habit: platy crystals.
Often confused with
Mathesiusite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside mathesiusite
Minerals reported to co-occur with mathesiusite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- K₅(UO₂)₄(SO₄)₄(VO₅)·4H₂O
- Mohs hardness
- ~2
- Density
- 4.018 g/cm³
- Colors
- Streak
- Greenish white
- Luster
- Vitreous
- Transparency
- Transparent to translucent
- Crystal system
- Tetragonal
- Crystal habit
- Platy crystals
- Cleavage
- Perfect on {110}, less perfect on {001}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A rare post-mining, secondary mineral in the underground workings in a polymetallic hydrothermal vein type deposit
Where rockhounds find mathesiusite
Classic worldwide localities
- Geschieber vein, fifth level of the Svornost (Einigkeit) mine, Jáchymov ore district, Western Bohemia, Czech Republic
Field-hunting tip
Where it forms: A rare post-mining, secondary mineral in the underground workings in a polymetallic hydrothermal vein type deposit. If you start seeing adolfpateraite, schoepite, čejkaite in float, you are in the right ground. Typical habit: platy crystals. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify mathesiusite?+
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What rocks look like mathesiusite?+
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Find mathesiusite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
