Kurilite is a rare silver telluride-selenide mineral typically found as microscopic grains within epithermal precious metal veins. It is notoriously difficult to identify without laboratory methods like electron microprobe analysis due to its small size and similarity to other silver tellurides.
Is this kurilite?
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 kurilite with a known reference. Kurilite sits at Mohs 3, 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, steel gray.
- 5Look at form & habitCrystal system: trigonal. Typical habit: anhedral grains, microscopic inclusions.
Often confused with
Kurilite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Kurilite leaves black, Hessite leaves light gray.
How to tell apart: Kurilite is noticeably harder (Mohs 3 vs. 1.5-2); streak differs, so Kurilite leaves black, Tellurobismuthite leaves pale lead-gray.
Often found alongside kurilite
Minerals reported to co-occur with kurilite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Ag₈Te₃Se
- Mohs hardness
- 3
- Density
- 7.799 g/cm³
- Colors
- Streak
- Black
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Trigonal
- Crystal habit
- Anhedral grains, microscopic inclusions
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector, Scientific research
- Host rock
- In hydrothermal Au-Ag quartz veins cutting calcalkaline volcanic rocks
Where rockhounds find kurilite
Classic worldwide localities
- Prasolovskoe epithermal Au-Ag deposit, Kunashir Island, Kuril arc, Russia
Field-hunting tip
Where it forms: In hydrothermal Au-Ag quartz veins cutting calcalkaline volcanic rocks. If you start seeing tetrahedrite, native gold, hessite in float, you are in the right ground. Typical habit: anhedral grains, microscopic inclusions. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify kurilite?+
Where is kurilite found?+
Is kurilite safe to handle?+
What rocks look like kurilite?+
What minerals are found with kurilite?+
What kind of rock does kurilite form in?+
What is kurilite used for?+
Find kurilite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
