Bournonite
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Bournonite was named in honor of Jacques Louis de Bournon (1751–1825), French crystallographer and mineralogist.

Discovered in 1805;   IMA status: Valid (pre-IMA; Grandfathered)

Chemistry

Chemical Formula:

PbCuSbS₃

Copper Lead Antimony Sulfide

Molecular Weight:

488.69 gm

Composition:

Copper

13.00 %

Cu

Antimony

24.91 %

Sb

Lead

42.40 %

Pb

Sulphur

19.68 %

S

100.00 %

Classification

Mineral Classification:

Sulfides

Strunz 8th Ed. ID:

2/E.16-20

Nickel-Strunz 10th Ed. ID:

2.GA.50

2 : SULFIDES and SULFOSALTS (sulfides, selenides, tellurides; arsenides, antimonides, bismuthides; sulfarsenites, sulfantimonites, sulfbismuthites, etc.)
G : Sulfarsenites, sulfantimonites, sulfbismuthites
A : Neso-sulfarsenites, etc. without additional S

Related to:

Bounonite Group. Seligmannite - Bournonite Series.

Members of Group:

Bounonite Group: Bournonite, Seligmannite

Varieties:

None

Synonyms:

Antimonial Copper, Antimonial Lead Ore, Berthonite, Bournonite (of Jameson), Cog Wheel Ore, Endellione, Endellionite, Plomb sulfuré antimonifère, Rädlerz, Schwarz Spiessglanzerz, Speissglanzblei, Tripelglanz, Wheel Ore, Wölchite

Crystal Data

Crystallography:

Orthorhombic - Dipyramidal

Crystal Habit:

Crystals short prismatic to tabular, typically striated, as much as 11 cm across; commonly as subparallel aggregates. Also massive, granular to compact.

Twinning:

Common on [110], often forms cross shapes, or if repeated, forms flat wheel shaped crystals called cog wheels.

Physical Properties

Cleavage:

Imperfect on {010}, less Perfect on {100} and {001}

Fracture:

Irregular/Uneven, Sub-Conchoidal

Tenacity:

Brittle

Moh's Hardness:

2.5 - 3.0

Density:

5.83 (g/cm³)

Luminescence:

None

Radioactivity:

Not Radioactive

Optical Properties

Color:

Gray, Steel Gray, Black, Iron Black

Transparency:

Opaque

Luster:

Metallic; Brilliant to Dull

Refractive Index:

n/a; Opaque

Birefringence:

n/a; Opaque

Dispersion:

n/a; Opaque

Pleochroism:

Very Weak

Weak; color in reflected light: White

Occurances

Geological Setting:

In hydrothermal veins formed at medium temperatures.

Common Associations:

Barite, Chalcopyrite, Dolomite, Galena, Pyrite, Quartz, Rhodochrosite, Siderite, Sphalerite, Stibnite, Tetrahedrite, Zinkenite

Common Impurities:

As, Ag, Fe, Zn, Mn, Ni

Type Locality:

Wheal Boys (Trewetha), St Endellion, Area East of Wadebridge, Wadebridge District, Cornwall, England, UK

Year Discovered:

1805

View mineral photos:

Bournonite Mineral Photos and Locations

More Information

Mindat.org
Webmineral.com

Bournonite is a metallic sulfide mineral found in many localities worldwide but very rarely faceted. The Bournonite mineral is also called the "cog wheel ore" because of the cog wheel shape that the twinned crystals commonly form. Bournonite has a bright, metallic, black luster and is very soft.

Bournonite is a fairly common mineral found in many localities worldwide including Machacamarca District, Saavedra Province, Potosí Department, Bolivia; Chenzhou Prefecture, Hunan Province, China; Gard, Languedoc-Roussillon, France; Altenkirchen, Wied Iron Spar District, Westerwald, Rhineland-Palatinate, Germany; Léssolo, Canavese District, Torino Province, Piedmont, Italy; Pachapaqui District, Bolognesi Province, Ancash Department, Peru; Cerro de Pasco, Daniel Alcides Carrión Province, Pasco Department, Peru; Maramures County, Romania; Silver King Mine, Park City District, Wasatch Mountains, Summit County, Utah, USA.
  

  
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