Aguilarite is a rare silver-selenium-sulfide mineral that typically forms in epithermal vein deposits. Collectors should look for its characteristic lead-gray metallic luster, often found as thin coatings or small clusters associated with other silver minerals in hydrothermal environments.
Is this aguilarite?
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 aguilarite with a known reference. Aguilarite sits at Mohs 2.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: grayish black.
- 3Read the lusterHold the specimen under a strong light. Luster: metallic.
- 4Match the color rangeCompare against the expected color range: gray, iron gray, black.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: massive.
Often confused with
Aguilarite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Aguilarite leaves grayish black, Acanthite leaves black.
How to tell apart: Streak differs, so Aguilarite leaves grayish black, Naumannite leaves black.
How to tell apart: Streak differs, so Aguilarite leaves grayish black, Argentite leaves black.
Often found alongside aguilarite
Minerals reported to co-occur with aguilarite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Ag₄SeS
- Mohs hardness
- 2.5
- Density
- 7.40-7.53 g/cm³
- Streak
- Grayish black
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Orthorhombic
- Crystal habit
- Massive
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- An uncommon, relatively low-temperature, mineral in hydrothermal deposits rich in silver and selenium, but manifestly deficient in sulfur
Where rockhounds find aguilarite
Classic worldwide localities
- Silver City, Owyhee Co., and at the 4th of July mine, Yankee Fork, Custer Co., Idaho, USA
- Comstock Lode, Virginia City, Storey Co., Nevada, USA
- L-D mine, Wenatchee, Chelan Co. and the Knob Hill mine, Republic, Ferry Co., Washington, USA
- Cuchillo, Winston district, Sierra Co., New Mexico, USA
- Guanajuato, in the San Carlos mine (type locality), Mexico
- Chontalpan mine, Taxco, Guerrero, Mexico
Field-hunting tip
Where it forms: An uncommon, relatively low-temperature, mineral in hydrothermal deposits rich in silver and selenium, but manifestly deficient in sulfur. If you start seeing acanthite, naumannite, silver in float, you are in the right ground. Typical habit: massive. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify aguilarite?+
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Is aguilarite safe to handle?+
What rocks look like aguilarite?+
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Find aguilarite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
