Tedhadleyite is a rare mercury oxide that forms dark red to black partially hollow, spheroidal masses. It was approved as a distinct mineral species in 2001. It was first described from a prospect pit near the former Clear Creek mercury mine, San Benito County, California, USA.
Is this tedhadleyite?
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 tedhadleyite with a known reference. Tedhadleyite 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. Tedhadleyite leaves a red streak.
- 3Read the lusterHold the specimen under a strong light. Tedhadleyite typically shows a adamantine to submetallic luster.
- 4Match the color rangeCompare against the expected color range: dark red, black.
- 5Look at form & habitCrystal system: triclinic. Typical habit: partially hollow, spheroidal masses.
Often confused with
Tedhadleyite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Tedhadleyite leaves red, Calomel leaves white; luster reads adamantine to submetallic on Tedhadleyite and adamantine on Calomel.
How to tell apart: Streak differs, so Tedhadleyite leaves red, Terlinguaite leaves yellow; luster reads adamantine to submetallic on Tedhadleyite and adamantine on Terlinguaite.
Often found alongside tedhadleyite
Minerals reported to co-occur with tedhadleyite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Hg²⁺Hg¹⁺₁₀O₄I₂(Cl,Br)₂
- Mohs hardness
- 2
- Density
- 9.43 g/cm³
- Streak
- Red
- Luster
- Adamantine to Submetallic
- Transparency
- Opaque
- Crystal system
- Triclinic
- Crystal habit
- Partially Hollow, Spheroidal Masses
- Cleavage
- Poor On {010}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Hydrothermal Veins in Carbonate Rocks
Where rockhounds find tedhadleyite
Classic worldwide localities
- prospect pit near the former Clear Creek mercury mine, California, USA
Field-hunting tip
Look in hydrothermal veins in carbonate rocks country, the host setting where tedhadleyite typically forms. If you start seeing cinnabar, pyrite, quartz in float, you are in the right ground. Field specimens usually show a partially hollow, spheroidal masses habit, so train your eye for that shape before scanning the outcrop.
Common questions
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Find tedhadleyite on the map
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