Mosesite is a rare mercury mineral typically found as tiny, brilliant lemon-yellow octahedral crystals. It is best known for its occurrence in the mercury-rich deposits of Terlingua, Texas, where it forms in close association with other rare mercury chlorides. Collectors prize it for its vibrant color and rarity, though it is usually found only in microscopic sizes.
Is this mosesite?
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 mosesite with a known reference. Mosesite sits at Mohs 3.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: very pale yellow.
- 3Read the lusterHold the specimen under a strong light. Luster: adamantine.
- 4Match the color rangeCompare against the expected color range: yellow, light green, olive green.
- 5Look at form & habitCrystal system: cubic. Typical habit: cubic crystals.
Often confused with
Mosesite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Mosesite is noticeably harder (Mohs 3.5 vs. 1.5); streak differs, so Mosesite leaves very pale yellow, Calomel leaves pale yellowish white.
How to tell apart: Mosesite is noticeably harder (Mohs 3.5 vs. 2.5); streak differs, so Mosesite leaves very pale yellow, Terlinguaite leaves lemon-yellow, turning olive-green; luster reads adamantine on Mosesite and brilliant adamantine on Terlinguaite.
Often found alongside mosesite
Minerals reported to co-occur with mosesite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (Hg₂N)Cl
- Mohs hardness
- 3.5
- Density
- 7.72 g/cm³
- Streak
- Very pale yellow
- Luster
- Adamantine
- Transparency
- Semitransparent
- Crystal system
- Cubic
- Crystal habit
- Cubic crystals
- Cleavage
- {111}, imperfect
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A rare secondary mineral formed at low temperature in hydrothermal mercury deposits
Where rockhounds find mosesite
Classic worldwide localities
- Terlingua, Brewster Co., Texas, USA
- T.S. Clack Quicksilver mine, about 37 km northeast of Lovelock, Fitting district, Mineral Co., and the McDermitt mine, Humboldt Co., Nevada, USA
- Clear Creek mercury mine, New Idria district, San Benito Co., California, USA
- Huahuaxtla, Guerrero, and El Doktor, Querétaro, Mexico
Field-hunting tip
Where it forms: A rare secondary mineral formed at low temperature in hydrothermal mercury deposits. If you start seeing calcite, cinnabar, metacinnabar in float, you are in the right ground. Typical habit: cubic crystals. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify mosesite?+
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Is mosesite safe to handle?+
What rocks look like mosesite?+
What minerals are found with mosesite?+
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Find mosesite on the map
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