Minerals.net Menu

The Mineral stephanite

Stephanite Crystal Clusters

Stephanite is an uncommon mineral that is composed with a significant portion of silver in its structure. It is an important ore mineral and mined for its silver content, and is almost always found in in known silver deposits. Stephanite mostly forms in massive ore habit that is uninteresting to collectors, but it is important as an economic commodity for its silver content. However, it does occasionally form in highly aesthetic and lustrous crystals that are highly valued among collections. Stephanite is named after Archduke Stephen Francis Victor of Austria (1817-1867).

Chemical Formula

Ag₅SbS₄

Color

Dark gray to nearly black. Occasionally iridescent. May tarnish dull black.

Crystal System

Orthorhombic

Properties

Streak
Black

Hardness
2 - 2.5

Transparency
Opaque

Specific Gravity
6.2 - 6.5

Luster
Metallic

Cleavage
2,2

Fracture
Uneven

Tenacity
Brittle

Crystal Habits

Forms as prismatic and tabular crystal, which are often vertically striated. Sometimes hexagonal in shape, due to twinning on the prism-planes, forming a trilling. Crystals may be hemimorphic, with six-sided prisms terminated by larger basal planes. Other habits include columnar, platy, in rosettes, in parallel groups, grainy, and massive.

3D Crystal Atlas

Additional Information

Composition
Silver antimony sulfide

In Group
Sulfides; Sulfosalts

Striking Features
Crystal habits, streak, and mode of occurrence.

Environment
Low temperature epithermal veins in silver ore deposits.

Rock Type
Sedimentary

Uses

Stephanite is an ore of silver. Well-formed crystals are hard to come across and are therefore highly valued among collectors.

Noteworthy Localities

Stephanite has been found in many of the classic silver deposits. Some of the best crystals of Stephanite were found at the Freiberg District, Erzgebirge, Saxony, Germany. Well-formed hexagonal crystals have come from St Andreasberg, Harz Mountains, Saxony, Germany; and another classic European locality is the Příbram region, Bohemia, Czech Republic.

The silver deposits in Potosí Department, Bolivia, have produced fine examples of Stephanite, especially at Porco where it was found in excellent parallel crystal groups. In Mexico, sharp crystal groups have come from Mexico at the Chispas (Pedrazzini) Mine, Arizpe, Sonora; Fresnillo, Zacatecas.

In the U.S., Stephanite was one of the important silver ores at the Comstock Lode in Virginia City, Storey Co., Nevada. In Canada, iridescent columnar crystals of Stephanite came from a one time find in the Husky Mine, Mayo Mining District, Yukon Territory.