Cerargyrite, commonly known as horn silver, is a secondary silver mineral found in the oxidized zones of silver deposits. It is notable for its soft, waxy, or horn-like appearance and its tendency to darken when exposed to light.
Is this cerargyrite?
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 cerargyrite with a known reference. Cerargyrite sits at Mohs 1.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: white.
- 3Read the lusterHold the specimen under a strong light. Luster: resinous.
- 4Match the color rangeCompare against the expected color range: colorless, white, gray, yellowish, brownish, violet.
- 5Look at form & habitCrystal system: cubic. Typical habit: massive, encrusting, cubic crystals.
Often confused with
Cerargyrite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Bromargyrite is the harder of the two (Mohs 2.5 vs. 1.5).
How to tell apart: Streak differs, so Cerargyrite leaves white, Iodargyrite leaves yellow, shining.
How to tell apart: Calcite is the harder of the two (Mohs 3 vs. 1.5); luster reads resinous on Cerargyrite and vitreous; pearly on cleavages and {0001} on Calcite.
Often found alongside cerargyrite
Minerals reported to co-occur with cerargyrite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- AgCl
- Mohs hardness
- 1.5
- Density
- 5.55 g/cm³
- Streak
- White
- Luster
- Resinous
- Transparency
- Translucent
- Crystal system
- Cubic
- Crystal habit
- Massive, encrusting, cubic crystals
- Cleavage
- None
- Rarity
- Uncommon
- Uses
- Collector, Ore of silver
- Host rock
- oxidized zones of silver ore deposits
Where rockhounds find cerargyrite
3 mapped spotsClassic worldwide localities
- Broken Hill, Australia
- Chañarcillo, Chile
- Guanajuato, Mexico
- Leadville, Colorado, USA
- Tsumeb, Namibia
Field-hunting tip
Where it forms: oxidized zones of silver ore deposits. If you start seeing silver, iodargyrite, bromargyrite in float, you are in the right ground. Typical habit: massive, encrusting, cubic crystals. Train your eye for that shape before scanning the outcrop. In the U.S., the densest reported localities are in New Mexico, Texas. Start trip planning there.
Common questions
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Find cerargyrite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
