What does chalcocite mean?
Chalcocite is a naturally occurring mineral composed of copper sulfide, Cu₂S, prized above all as one of the world's most important ores of copper. It typically appears as dark grey to black masses or tabular crystals with a strong metallic lustre — so striking when freshly exposed that miners once called it 'copper glance'. Soft enough to be scratched by a knife, it usually forms in the upper, enriched zones of copper deposits, where chemical processes concentrate copper minerals over time. Because of its high copper content, chalcocite has been a major target of mining operations for centuries, and the metal extracted from it goes into wiring, plumbing, and countless manufactured goods. The word belongs to the specialized vocabulary of mineralogists, geologists, and mining engineers rather than everyday English, but it remains a key term in any discussion of copper resources and ore formation.
nounA lustrous dark grey to black metallic mineral consisting of copper sulfide (Cu₂S), and the most important ore of copper after chalcopyrite.
- A soft, dark grey to black metallic mineral, copper sulfide (Cu₂S), crystallizing in the orthorhombic system and serving as one of the most important ores of copper.
"The miners traced a rich vein of chalcocite through the limestone, knowing its high copper content made the deposit especially valuable."
"Beneath the zone of oxidation, the ore body consisted almost entirely of massive chalcocite."
"Under the microscope, the polished section revealed chalcocite rims replacing earlier chalcopyrite grains."
As a mass noun denoting a substance, chalcocite is usually uncountable; the plural occurs mainly when referring to distinct specimens, varieties, or occurrences of the mineral.
"The museum's collection includes chalcocites from Cornwall and Montana."
Its old miner's name, 'copper glance', captures how this dull-looking black mineral flashes with an almost mirror-like metallic shine when freshly broken — and it can hold nearly 80% copper by weight.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of chalcocite
Chalcocite derives from the Greek word 'khalkos', meaning copper, combined with the mineral-name suffix '-ite'; it was named in the mid-nineteenth century as part of the systematic naming of newly classified minerals. The same Greek root appears in related scientific terms such as 'chalcolithic' (the Copper Age) and 'chalcopyrite', another important copper ore. An older English name for the mineral was 'copper glance', a translation of German usage that has since fallen out of favour.
How chalcocite is actually used
A technical term used chiefly in mineralogy, geology, and mining; it rarely appears in everyday speech. The historical synonym 'copper glance' is now largely obsolete.
Easily confused with chalcocite
Chalcopyrite is a copper iron sulfide (CuFeS₂) with a brassy yellow colour, whereas chalcocite is a darker grey-black copper sulfide (Cu₂S) that is richer in copper.