Empressite is a rare silver telluride mineral often found as granular masses in hydrothermal gold-telluride deposits. It is best identified by its metallic luster, black streak, and association with other telluride minerals, though it is frequently intergrown with or replaced by hessite.
Is this empressite?
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 empressite with a known reference. Empressite 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: gray-black to black.
- 3Read the lusterHold the specimen under a strong light. Luster: metallic.
- 4Match the color rangeCompare against the expected color range: bronze, light bronze.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: compact.
Often confused with
Empressite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Empressite is noticeably harder (Mohs 3.5 vs. 1.5-2); streak differs, so Empressite leaves gray-black to black, Sylvanite leaves steel-gray to silver-white.
How to tell apart: Streak differs, so Empressite leaves gray-black to black, Hessite leaves light gray.
How to tell apart: Streak differs, so Empressite leaves gray-black to black, Petzite leaves grayish black.
Often found alongside empressite
Minerals reported to co-occur with empressite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- AgTe
- Mohs hardness
- 3.5
- Density
- 7.61 g/cm³
- Colors
- BronzeLight bronze
- Streak
- Gray-black to black
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Orthorhombic
- Crystal habit
- Compact
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- In low-temperature gold-poor hydrothermal vein deposits
Where rockhounds find empressite
Classic worldwide localities
- Empress Josephine mine, Kerber Creek district (type locality), and the Klondike mine, Finley Gulch, both in Saguache Co., Colorado, USA
- May Day mine, La Plata Co., Colorado, USA
- Red Cloud, Rex, and other mines, Boulder Co., Colorado, USA
- Tombstone, Cochise Co., Arizona, USA
- Grotto group of pits, near Pitman, British Columbia, and the Quetico intrusions, northwestern, Ontario, Canada
- Kalgoorlie, Western Australia
Field-hunting tip
Where it forms: In low-temperature gold-poor hydrothermal vein deposits. If you start seeing tellurium, sylvanite, petzite in float, you are in the right ground. Typical habit: compact. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify empressite?+
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Find empressite on the map
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