Hutchinsonite is a rare thallium-arsenic sulfosalt often found as small, deep red, translucent crystals. It is highly sought after by collectors for its beauty, though it requires cautious handling due to its toxic heavy metal content.
Is this hutchinsonite?
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 hutchinsonite with a known reference. Hutchinsonite sits at Mohs 1.5-2, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: red.
- 3Read the lusterHold the specimen under a strong light. Luster: adamantine to submetallic.
- 4Match the color rangeCompare against the expected color range: cherry red, pink, black.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: acicular, prismatic.
Often confused with
Hutchinsonite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Hutchinsonite leaves red, Realgar leaves red-orange to red; luster reads adamantine to submetallic on Hutchinsonite and resinous to greasy on Realgar.
How to tell apart: Streak differs, so Hutchinsonite leaves red, Orpiment leaves pale lemon-yellow; luster reads adamantine to submetallic on Hutchinsonite and resinous, pearly on cleavage surface on Orpiment.
How to tell apart: Streak differs, so Hutchinsonite leaves red, Smithite leaves vermilion.
Often found alongside hutchinsonite
Minerals reported to co-occur with hutchinsonite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (Tl,Pb)₂As₅S₉
- Mohs hardness
- 1.5-2
- Density
- 4.6-4.7 g/cm³
- Streak
- Red
- Luster
- Adamantine to submetallic
- Transparency
- Opaque, translucent in thin fragments
- Crystal system
- Orthorhombic
- Crystal habit
- Acicular, prismatic
- Cleavage
- Good on {010}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Of hydrothermal origin
Where rockhounds find hutchinsonite
Classic worldwide localities
- Lengenbach quarry, Binntal, Valais (type locality), Switzerland
- Segen Gottes mine, near Wiesloch, Black Forest, Germany
- La Libertad mine, Quiruvilca, Peru
- Toya-Takarada mine, Hokkaido, Japan
- Nanhua Sn–Tl deposit, Yunnan Province, China
Field-hunting tip
Where it forms: Of hydrothermal origin. If you start seeing orpiment, realgar, getchellite in float, you are in the right ground. Typical habit: acicular, prismatic. Train your eye for that shape before scanning the outcrop.
Common questions
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Find hutchinsonite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
