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 — 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 — 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 — that is 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.
