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Stephanite
Stephanite is sulfosalts, Ag5SbS4. In the hand, it rates 2 to 2.5 on the Mohs scale, and it runs iron black and lead gray with black tarnish. Black metallic tablets and short prisms, very heavy, very soft, and famously brittle, edges crumble where acanthite would carve like lead.
The geology.
Stephanite carries the formula Ag5SbS4. It belongs to the orthorhombic system. Its listing category is sulfosalts.
It sits at 2 to 2.5 on the Mohs scale. The surface reads metallic. Light behaviour is opaque. Specific gravity runs 6.25 to 6.43. The streak is iron black, shining. It breaks with poor cleavage; subconchoidal brittle fracture.
Black metallic tablets and short prisms, very heavy, very soft, and famously brittle, edges crumble where acanthite would carve like lead.
It turns up mostly as short prismatic and tabular crystals, pseudo-hexagonal twins or massive vein ore.
The origins.
Silver veins: Freiberg (Germany, classic), Zacatecas and Fresnillo (Mexico), Comstock Lode (Nevada), Pribram (Czechia).
On value, the database notes: collector mineral; sharp Freiberg or Mexican crystals are valued classics.
Traditional associations.
In energy work traditions, associated with releasing brittle defenses and grounding ambition.
This is lore, and we label it as lore. The measurable facts are further up the page.
Spotting the real thing.
Black metallic tablets and short prisms, very heavy, very soft, and famously brittle, edges crumble where acanthite would carve like lead.
Not faked; mislabeled acanthite is frequent, the brittleness test separates them.
| Looks like | How to tell them apart |
|---|---|
| Acanthite/argentite | Acanthite is sectile, a knife cuts curls; stephanite crumbles (hence brittle silver) |
| Galena | Galena cleaves into perfect cubes; stephanite shows no cubic cleavage |
| Tetrahedrite | Tetrahedrite is harder (3.5 to 4) and forms tetrahedral crystals |
At-home tests.
A loupe and a window seat settle most questions about stephanite. No workshop required.
| Test | What you should see |
|---|---|
| By eye | Brittleness vs acanthite's sectility |
| By eye | Soft (2 to 2.5) and SG over 6 |
| By eye | Shining black streak |
If these checks leave you unsure, that is what appraisers are for. Do not file, heat or soak a piece to find out.
Care & handling.
At 2 to 2.5 on the Mohs scale this is a soft material. Keep it as a display piece, store it apart from harder stones, and skip daily-wear settings.
It breaks with poor cleavage; subconchoidal brittle fracture, which is worth knowing before you set it or drop it.
Most damage happens during cleaning, not wearing. Avoid steamers, ultrasonic tanks and anything from under the sink.
Contains antimony and silver sulfide: wash hands after handling, no elixirs.
A deeper look.
Extended detail on composition, sourcing, authentication and market value.
The physical record
The formula on record is Ag5SbS4. Crystal system: Orthorhombic. Specific gravity: 6.25 to 6.43. Streak: Iron black, shining. Cleavage and fracture: Poor cleavage; subconchoidal brittle fracture.
How it reaches the market
Silver veins: Freiberg (Germany, classic), Zacatecas and Fresnillo (Mexico), Comstock Lode (Nevada), Pribram (Czechia).
What it gets confused with
Acanthite/argentite: Acanthite is sectile, a knife cuts curls; stephanite crumbles (hence brittle silver). Galena: Galena cleaves into perfect cubes; stephanite shows no cubic cleavage. Tetrahedrite: Tetrahedrite is harder (3.5 to 4) and forms tetrahedral crystals.
What it is worth
Collector mineral; sharp Freiberg or Mexican crystals are valued classics.
Where buyers get caught
Not faked; mislabeled acanthite is frequent, the brittleness test separates them.
One more thing
On the Comstock Lode stephanite was a main ore of the silver bonanza that built Virginia City, miners called all the dark silver ores 'black sulphurets'.
An education-first guide.
There is nothing to buy on this page. Stephanite is not part of our catalogue, and the guide is here anyway because somebody searching the name deserves a straight answer.
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