Kleinite is a rare mercury-ammonium chloride sulfate mineral that forms distinct, bright yellow hexagonal crystals. It is primarily found in the oxidized zones of mercury deposits, frequently occurring alongside other rare mercury halides.
Is this kleinite?
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 kleinite with a known reference. Kleinite sits at Mohs 3.5-4, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: sulfur-yellow.
- 3Read the lusterHold the specimen under a strong light. Luster: adamantine to greasy.
- 4Match the color rangeCompare against the expected color range: yellow, orange.
- 5Look at form & habitCrystal system: hexagonal. Typical habit: prismatic.
Often confused with
Kleinite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Kleinite is noticeably harder (Mohs 3.5-4 vs. 2.5); streak differs, so Kleinite leaves sulfur-yellow, Eglestonite leaves yellow or greenish yellow, rapidly becoming black; luster reads adamantine to greasy on Kleinite and brilliant adamantine to resinous on Eglestonite.
How to tell apart: Kleinite is noticeably harder (Mohs 3.5-4 vs. 2.5); streak differs, so Kleinite leaves sulfur-yellow, Terlinguaite leaves lemon-yellow, turning olive-green; luster reads adamantine to greasy on Kleinite and brilliant adamantine on Terlinguaite.
Often found alongside kleinite
Minerals reported to co-occur with kleinite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Hg₂N(Cl,SO₄)·nH₂O
- Mohs hardness
- 3.5-4
- Density
- 7.9-8.0 g/cm³
- Streak
- Sulfur-yellow
- Luster
- Adamantine to greasy
- Transparency
- Transparent to translucent
- Crystal system
- Hexagonal
- Crystal habit
- Prismatic
- Cleavage
- {0001}, uneven; {1010}, imperfect
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In hydrothermal mercury deposits
Where rockhounds find kleinite
Classic worldwide localities
- Terlingua, Brewster Co., Texas, USA
- New Idria district, San Benito Co., California, USA
- McDermitt and Cordero mercury mines, Opalite district, Humboldt Co., Nevada, USA
Field-hunting tip
Where it forms: In hydrothermal mercury deposits. If you start seeing terlinguaite, gypsum, barite in float, you are in the right ground. Typical habit: prismatic. Train your eye for that shape before scanning the outcrop.
Common questions
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Find kleinite on the map
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