Sterryite is a rare lead-silver sulfosalt mineral primarily known for its distinct acicular or fibrous habit. It is found in hydrothermal vein deposits and is most famously associated with the type locality in Madoc, Ontario, where it forms delicate gray-black aggregates.
Is this sterryite?
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 sterryite with a known reference. Sterryite 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: black.
- 3Read the lusterHold the specimen under a strong light. Luster: metallic.
- 4Match the color rangeCompare against the expected color range: black.
- 5Look at form & habitCrystal system: orthorhombic. Typical habit: plumose.
Often confused with
Sterryite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Sterryite is noticeably harder (Mohs ~3.5 vs. 2.5); streak differs, so Sterryite leaves black, Jamesonite leaves black. grayish.
How to tell apart: Streak differs, so Sterryite leaves black, Boulangerite leaves brownish.
How to tell apart: Streak differs, so Sterryite leaves black, Bournonite leaves steel-gray to iron-black; luster reads metallic on Sterryite and brilliant to dull on Bournonite.
Often found alongside sterryite
Minerals reported to co-occur with sterryite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Cu(Ag,Cu)₃Pb₁₉(Sb,As)₂₂(As₂)S₅₆
- Mohs hardness
- ~3.5
- Density
- 6 g/cm³
- Colors
- Streak
- Black
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Orthorhombic
- Crystal habit
- Plumose
- Cleavage
- Perfect on {hk0}
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Of hydrothermal origin, in marble
Where rockhounds find sterryite
Classic worldwide localities
- Taylor pit, Madoc, Huntingdon township, Hastings County, Ontario, Canada (type locality)
Field-hunting tip
Where it forms: Of hydrothermal origin, in marble. If you start seeing veenite, guettardite in float, you are in the right ground. Typical habit: plumose. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify sterryite?+
Where is sterryite found?+
Is sterryite safe to handle?+
What rocks look like sterryite?+
What minerals are found with sterryite?+
What kind of rock does sterryite form in?+
What is sterryite used for?+
Find sterryite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
