Freibergite

A variety of Minerals

What is Freibergite?

Freibergite is a complex sulfosalt mineral of silver, copper, iron, antimony and arsenic with formula (Ag,Cu,Fe)12(Sb,As)4S13. It has cubic crystals and is formed in hydrothermal deposits. It forms one solid solution series with tetrahedrite and another with argentotennantite. Freibergite is an opaque, metallic steel grey to black and leaves a reddish-black streak. It has a Mohs hardness of 3.5 to 4.0 and a specific gravity of 4.85 - 5. It is typically massive to granular in habit with no cleavage and an irregular fracture. The mineral was first described in 1853 from an occurrence in the silver mines of the type locality at Freiberg, Saxony.

Market Value Factors

Pricing varies for every rock and mineral, so use these universal factors to gauge Freibergite before comparing listings or appraisals.

Size & Weight

Larger, intact specimens usually command higher prices.

Rarity & Demand

Scarce material or popular varieties sell at a premium.

Condition & Finish

Chips, repairs, and heavy wear lower value; clean prep helps.

Treatment & Provenance

Untreated specimens with documented locality are prized.

Applies to all rocks & minerals.

Freibergite Localities Map

See where Freibergite is found with a localities map, collecting zones, and geology context. Generate a sample map preview below.

Map preview

North ZoneCentral RidgeSouth Basin

More Images

Robert M. Lavinsky

Quick Facts

Physical Properties

Color: Grey
Hardness (Mohs): 3.5 - 4
Density: 5.41 g/cm³
Streak: Reddish black

Chemical Properties

Chemical Formula: (Ag,Cu,◻)₁₀Fe²⁺2Sb₄S₁₂◻ May also be expressed as (Ag⁴⁺2xCu^2-2x)[(Cu,Ag)₄(Fe,Zn)₂]Sb₄S₁₂S^1-x (0 < x < 1). Note however that if x < 1, this suggested formula cannot be charge balanced.
Elements: Ag, Cu, Fe, S, Sb