Bornite
Bornite is a sulfide mineral known for its striking metallic crystals, with several world-class Chinese localities.
About Bornite
Bornite is a sulfide mineral in the bornite group and has the chemical formula Cu5FeS4. It crystallizes in the orthorhombic system and is relatively soft, requiring careful handling. Its combination of structural character and global distribution make it a recognized species in both systematic and aesthetic collections.
Identification & care
Specimens usually show cubic, dodecahedral, octahedral crystals (rare); usually massive or granular. Its color is typically copper-red to pinchbeck-brown. The luster is metallic, the streak is grey-black, and specimens are typically opaque. The cleavage is poor/indistinct on {111}. The fracture is irregular/uneven, which aids identification.
Collector context
How it forms
The geological setting for Bornite is typically hydrothermal copper deposits, porphyry copper systems, contact metasomatic zones; frequently found as exsolution product with chalcopyrite. It is commonly found in association with chalcopyrite, chalcocite, pyrite, galena, covellite, native copper.
Classic Chinese localities
**Jiama Cu-polymetallic deposit**, **Dexing Cu-Mo-Au ore field** and **Huanggang Fe-Sn deposit** are an important Chinese source for the species.
Why collectors care
Bornite is among the most visually dramatic sulfides and native metals a collector can own. Bright metallic faces, sharp crystal geometry, and good matrix contrast make a single well-selected piece carry an entire cabinet; luster integrity and termination sharpness ultimately define its collector value.
What affects value
Value in Bornite is assessed, in typical order of weight, against: (1) locality provenance; (2) crystal size; (3) termination quality and crystal completeness; (4) metallic luster integrity (absence of tarnish); (5) crystal habit elegance (parallel, radiating, or bladed); (6) matrix contrast and aesthetic balance; (7) condition and absence of re-attached crystals. Verified locality documentation and absence of cleaning residue act as strong multipliers across the above.
Naming history
The name Bornite has a specific etymological and historical context — see Mindat's reference entry for provenance details. We have retained naming data at the record level; published prose is paraphrased from factual fields rather than copied from source.