Hanawaltite is an extremely rare mercury-lead oxychloride mineral found in oxidized mineral deposits. It typically occurs as small, brittle, dark brown platy crystals that form in high-grade oxidized zones.
Is this hanawaltite?
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 hanawaltite with a known reference. Hanawaltite sits at Mohs <5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: black to dark red-brown.
- 3Read the lusterHold the specimen under a strong light. Luster: metallic.
- 4Match the color rangeCompare against the expected color range: black, dark brown black, dark red brown.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: anhedral grains.
Often confused with
Hanawaltite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Hanawaltite is noticeably harder (Mohs <5 vs. 2.5); streak differs, so Hanawaltite leaves black to dark red-brown, Eglestonite leaves yellow or greenish yellow, rapidly becoming black; luster reads metallic on Hanawaltite and brilliant adamantine to resinous on Eglestonite.
How to tell apart: Hanawaltite is noticeably harder (Mohs <5 vs. 2.5); streak differs, so Hanawaltite leaves black to dark red-brown, Terlinguaite leaves lemon-yellow, turning olive-green; luster reads metallic on Hanawaltite and brilliant adamantine on Terlinguaite.
Often found alongside hanawaltite
Minerals reported to co-occur with hanawaltite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Hg₆HgO₃Cl₂
- Mohs hardness
- <5
- Density
- 9.52 g/cm³
- Colors
- Streak
- Black to dark red-brown
- Luster
- Metallic
- Transparency
- Opaque to translucent on very thin edges
- Crystal system
- Orthorhombic
- Crystal habit
- Anhedral grains
- Cleavage
- {001}, good
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A rare alteration product of cinnabar, in a mercury deposit in silicate-carbonate rock hydrothermally altered from serpentinite
Where rockhounds find hanawaltite
Classic worldwide localities
- Clear Creek mercury mine, New Idria district, San Benito Co., California, USA
Field-hunting tip
Where it forms: A rare alteration product of cinnabar, in a mercury deposit in silicate-carbonate rock hydrothermally altered from serpentinite. If you start seeing calomel, mercury, cinnabar in float, you are in the right ground. Typical habit: anhedral grains. Train your eye for that shape before scanning the outcrop.
Common questions
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Find hanawaltite on the map
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