Prachařite is a rare calcium antimony arsenic oxide. It was approved as a distinct mineral species in 2018. It was first described from Plaka Mine No. 80, Plaka, Lavrion District, Attikí Prefecture, Greece.
Is this prachařite?
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 prachařite with a known reference. Prachařite 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. Prachařite leaves a yellow streak.
- 3Read the lusterHold the specimen under a strong light. Prachařite typically shows a resinous luster.
- 4Match the color rangeCompare against the expected color range: yellow, brownish-yellow.
- 5Look at form & habitCrystal system: hexagonal. Typical habit: platy crystals, crusts.
Often confused with
Prachařite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Eskebornite is the harder of the two (Mohs 3-3.5 vs. 2); streak differs, so Prachařite leaves yellow, Eskebornite leaves black; luster reads resinous on Prachařite and metallic on Eskebornite.
How to tell apart: Streak differs, so Prachařite leaves yellow, Clausthalite leaves gray-black; luster reads resinous on Prachařite and metallic on Clausthalite.
Often found alongside prachařite
Minerals reported to co-occur with prachařite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- CaSb⁵⁺₂(As³⁺₂O₅)₂O₂(H₂O)₇·3H₂O
- Mohs hardness
- 2
- Density
- 4.92 g/cm³
- Colors
- Streak
- Yellow
- Luster
- Resinous
- Transparency
- Translucent
- Crystal system
- Hexagonal
- Crystal habit
- Platy Crystals, Crusts
- Cleavage
- Perfect On {001}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Hydrothermal Veins
Where rockhounds find prachařite
Classic worldwide localities
- Plaka Mine No. 80, Plaka, Lavrion District, Attikí Prefecture, Greece
Field-hunting tip
Look in hydrothermal veins country, the host setting where prachařite typically forms. If you start seeing eskebornite, clausthalite, pyrite in float, you are in the right ground. Field specimens usually show a platy crystals, crusts habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find prachařite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
