Bournonite is a mineral that belongs to the sulfosalt group, specifically the tetrahedrite series. It is composed of a combination of lead, copper, antimony, and sulfur. The name "Bournonite" is derived from its discovery location in Cornwall, England, specifically the Bournon mine.
Physically, Bournonite typically forms prismatic or pyramidal crystals, often with complex twinning patterns. Its color ranges from steel gray to dark gray, occasionally exhibiting iridescent hues. Bournonite has a metallic luster and a distinctive very high density. It can sometimes display a cubic cleavage, although this is relatively rare.
In terms of its properties, Bournonite is known for being a dense and heavy mineral, with an approximate specific gravity of 5.8 to 5.9. Its hardness typically falls between 2.5 and 3 on the Mohs scale, making it a relatively soft mineral. Bournonite has a non-metallic to sub-metallic to metallic appearance, depending on the specific crystal structure.
Bournonite is primarily valued for its aesthetic appeal, as it forms intricate, twinned crystals that can be found in a variety of mineral-rich environments. It is often sought after by mineral collectors due to its unique crystal habit, high density, and metallic luster. Bournonite can also serve as an important ore for extracting lead and copper, though it is not as commonly used for this purpose compared to other minerals.
In summary, Bournonite is a sulfosalt mineral composed of lead, copper, antimony, and sulfur. It is known for its dense, metallic appearance, and forms intricate, twinned crystals.
