Lorandite is a rare thallium arsenic sulfosalt often found in low-temperature hydrothermal deposits. It is best known by collectors for its distinct cherry-red streak and its historical importance in solar neutrino detection experiments.
Is this lorandite?
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 lorandite with a known reference. Lorandite sits at Mohs 2-2.5 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Lorandite leaves a cherry-red streak.
- 3Read the lusterHold the specimen under a strong light. Lorandite typically shows a metallic luster.
- 4Match the color rangeCompare against the expected color range: lead-gray, black, red internal reflections.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: prismatic or tabular crystals, massive.
Often confused with
Lorandite vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Lorandite leaves cherry-red, Realgar leaves orange-red; luster reads metallic on Lorandite and resinous on Realgar.
How to tell apart: Streak differs — Lorandite leaves cherry-red, Stibnite leaves lead-gray.
How to tell apart: Streak differs — Lorandite leaves cherry-red, Galena leaves lead-gray.
Often found alongside lorandite
Minerals reported to co-occur with lorandite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- TlAsS₂
- Mohs hardness
- 2-2.5
- Density
- 5.5 g/cm³
- Streak
- Cherry-red
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Monoclinic
- Crystal habit
- Prismatic or Tabular Crystals, Massive
- Cleavage
- Perfect in One Direction
- Rarity
- Rare
- Uses
- Collector, Scientific Research
- Host rock
- Hydrothermal Veins in Carbonate Rocks
- Typical price
- $50-500 depending on crystal quality and size
Where rockhounds find lorandite
Classic worldwide localities
- Allchar, North Macedonia
- Lengenbach, Binntal, Switzerland
- Jas Roux, France
Field-hunting tip
Look in hydrothermal veins in carbonate rocks country — that is the host setting where lorandite typically forms. If you start seeing realgar, orpiment, pyrite in float, you are in the right ground. Field specimens usually show a prismatic or tabular crystals, massive habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find lorandite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
