Lorándite is a rare thallium-arsenic sulfosalt that forms striking, dark red crystals. It is best known for being the mineral used in solar neutrino experiments and is typically found in low-temperature hydrothermal veins associated with other arsenic sulfides.
Is this lorándite?
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 lorándite with a known reference. Lorándite 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. Lorándite leaves a cherry red streak.
- 3Read the lusterHold the specimen under a strong light. Lorándite typically shows a metallic to submetallic luster.
- 4Match the color rangeCompare against the expected color range: dark red, crimson, cherry red.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: prismatic crystals, often striated.
Often confused with
Lorándite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Lorándite leaves cherry red, Realgar leaves orange-red; luster reads metallic to submetallic on Lorándite and resinous on Realgar.
How to tell apart: Streak differs, so Lorándite leaves cherry red, Proustite leaves scarlet; luster reads metallic to submetallic on Lorándite and adamantine on Proustite.
Often found alongside lorándite
Minerals reported to co-occur with lorándite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- TlAsS₂
- Mohs hardness
- 2
- Density
- 5.53 g/cm³
- Streak
- Cherry Red
- Luster
- Metallic to Submetallic
- Transparency
- Translucent
- Crystal system
- Monoclinic
- Crystal habit
- Prismatic Crystals, Often Striated
- Cleavage
- Perfect in One Direction
- Rarity
- Rare
- Uses
- Collector, Research
- Host rock
- Hydrothermal Mineral Deposits
- Typical price
- $50-500 thumbnail depending on crystal quality
Where rockhounds find lorándite
1 mapped spotsClassic worldwide localities
- Allchar, North Macedonia
- Jas Roux, France
- Lengenbach, Switzerland
Field-hunting tip
Look in hydrothermal mineral deposits country, the host setting where lorándite typically forms. If you start seeing realgar, orpiment, pyrite in float, you are in the right ground. Field specimens usually show a prismatic crystals, often striated habit, so train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in Wyoming. Start trip planning there.
Common questions
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Find lorándite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
