Radtkeite is a rare mercury halide sulfide mineral typically found as small, orange crystals in oxidized mercury deposits. It is specifically known from the McDermitt mine in Nevada, often occurring as encrustations associated with other mercury-bearing minerals. Because it is highly rare and contains mercury, it is sought after primarily by advanced mineral collectors.
Is this radtkeite?
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 radtkeite with a known reference. Radtkeite sits at Mohs 2-3, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: yellow-orange, blackening on exposure to light.
- 3Read the lusterHold the specimen under a strong light. Luster: nearly adamantine (synthetic).
- 4Match the color rangeCompare against the expected color range: orange, bright yellow orange.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: microscopic crystals.
Often confused with
Radtkeite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Radtkeite leaves yellow-orange, blackening on exposure to light, Cinnabar leaves scarlet; luster reads nearly adamantine (synthetic) on Radtkeite and adamantine, inclining to metallic when dark; dull in friable material on Cinnabar.
How to tell apart: Streak differs, so Radtkeite leaves yellow-orange, blackening on exposure to light, Calomel leaves pale yellowish white; luster reads nearly adamantine (synthetic) on Radtkeite and adamantine on Calomel.
How to tell apart: Luster reads nearly adamantine (synthetic) on Radtkeite and vitreous to adamantine on Kadyrelite.
Often found alongside radtkeite
Minerals reported to co-occur with radtkeite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Hg₃S₂ClI
- Mohs hardness
- 2-3
- Density
- 7.0 g/cm³
- Colors
- OrangeBright yellow orange
- Streak
- Yellow-orange, blackening on exposure to light
- Luster
- Nearly adamantine (synthetic)
- Transparency
- Opaque to translucent
- Crystal system
- Monoclinic
- Crystal habit
- Microscopic crystals
- Cleavage
- Perfect on {010}; very good on {001}; very good on {100}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In tuffaceous rhyolitic lake-bed sediments, formed as a reaction product between halide-bearing hydrothermal solutions and cinnabar or corderoite
Where rockhounds find radtkeite
Classic worldwide localities
- McDermitt mercury mine, Opalite district, Humboldt Co., Nevada, USA
Field-hunting tip
Where it forms: In tuffaceous rhyolitic lake-bed sediments, formed as a reaction product between halide-bearing hydrothermal solutions and cinnabar or corderoite. If you start seeing cinnabar, corderoite, quartz in float, you are in the right ground. Typical habit: microscopic crystals. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify radtkeite?+
Where is radtkeite found?+
Is radtkeite safe to handle?+
What rocks look like radtkeite?+
What minerals are found with radtkeite?+
What kind of rock does radtkeite form in?+
What is radtkeite used for?+
Find radtkeite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
