Ourayite is a rare silver-lead-bismuth sulfosalt that typically occurs as small, lead-gray metallic grains within hydrothermal ore deposits. It is notoriously difficult to identify in the field and usually requires chemical analysis or X-ray diffraction to confirm from similar-looking gray sulfides.
Is this ourayite?
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 ourayite with a known reference. Ourayite sits at Mohs 2, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: black.
- 3Read the lusterHold the specimen under a strong light. Luster: metallic.
- 4Match the color rangeCompare against the expected color range: gray.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: bladed, microscopic crystals.
Often confused with
Ourayite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Ourayite leaves black, Galena leaves lead-gray.
How to tell apart: Streak differs, so Ourayite leaves black, Aikinite leaves grayish black.
How to tell apart: Streak differs, so Ourayite leaves black, Matildite leaves pale gray.
Often found alongside ourayite
Minerals reported to co-occur with ourayite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Ag₃Pb₄Bi₅S₁₃
- Mohs hardness
- 2
- Density
- 7.11 g/cm³
- Colors
- Streak
- Black
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Orthorhombic
- Crystal habit
- Bladed, microscopic crystals
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In a hydrothermal sulfide vein (Old Lout mine, Colorado, USA); with topaz and fluorite in a cryolite body (Ivigtut, Greenland); with base-metal sulfides in diopside tactite (Pitiquito, Mexico)
Where rockhounds find ourayite
Classic worldwide localities
- Colorado, near Ouray, San Juan Co., from the Old Lout mine (type locality), in the Alaska mine, Poughkeepsie Gulch, USA
- Wombat mine, Montezuma district, Summit Co., Alaska, USA
- Comstock mine, La Plata Co., Alaska, USA
- South Mountain, Owyhee Co., Idaho, USA
- A tungsten prospect, 40 km south of Pitiquito, Sonora, Mexico
- Ivigtut cryolite deposit, southwestern Greenland
Field-hunting tip
Where it forms: In a hydrothermal sulfide vein (Old Lout mine, Colorado, USA); with topaz and fluorite in a cryolite body (Ivigtut, Greenland); with base-metal sulfides in diopside tactite (Pitiquito, Mexico). If you start seeing galena, matildite, berryite in float, you are in the right ground. Typical habit: bladed, microscopic crystals. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify ourayite?+
Where is ourayite found?+
Is ourayite safe to handle?+
What rocks look like ourayite?+
What minerals are found with ourayite?+
What kind of rock does ourayite form in?+
What is ourayite used for?+
Find ourayite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
