Iltisite is an extremely rare mercury halide mineral typically found as small, vibrant yellow platy crystals. It is primarily known from its type locality in Austria, where it occurs as a secondary mineral in association with other mercury species. Collectors prize it for its scarcity and distinct crystalline appearance within mercury-rich mineral assemblages.
Is this iltisite?
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 iltisite with a known reference. Iltisite 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. Streak: red.
- 3Read the lusterHold the specimen under a strong light. Luster: adamantine.
- 4Match the color rangeCompare against the expected color range: red, brownish red.
- 5Look at form & habitCrystal system: hexagonal. Typical habit: disseminated, platy.
Often confused with
Iltisite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Iltisite leaves red, Calomel leaves pale yellowish white.
How to tell apart: Streak differs, so Iltisite leaves red, Terlinguaite leaves lemon-yellow, turning olive-green; luster reads adamantine on Iltisite and brilliant adamantine on Terlinguaite.
Often found alongside iltisite
Minerals reported to co-occur with iltisite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- HgAgSCl
- Mohs hardness
- 2
- Density
- 6.59 g/cm³
- Colors
- Streak
- Red
- Luster
- Adamantine
- Transparency
- Translucent
- Crystal system
- Hexagonal
- Crystal habit
- Disseminated, platy
- Cleavage
- Perfect on {001}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In small cavities in conglomerate
Where rockhounds find iltisite
Classic worldwide localities
- The Cap Garonne mine, near Le Pradet, Var, France (type locality)
Field-hunting tip
Where it forms: In small cavities in conglomerate. If you start seeing cinnabar, calomel, terlinguaite in float, you are in the right ground. Typical habit: disseminated, platy. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify iltisite?+
Where is iltisite found?+
Is iltisite safe to handle?+
What rocks look like iltisite?+
What minerals are found with iltisite?+
What kind of rock does iltisite form in?+
What is iltisite used for?+
Find iltisite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
