Clausthalite

Discovered in 1832; IMA status: Valid (pre-IMA; Grandfathered)

Chemistry

Chemical Formula:

PbSe

Lead Selenide

Molecular Weight:

286.16 gm

Composition:

Lead

72.41 %

Pb

Selenium

27.59 %

Se

100.00 %

Classification

Mineral Classification:

Sulfides and Sulfosalts

Strunz 8th Ed. ID:

2/C.15-50

Nickel-Strunz 10th Ed. ID:

2.CD.10

2 : SULFIDES and SULFOSALTS (sulfides, selenides, tellurides; arsenides, antimonides, bismuthides; sulfarsenites, sulfantimonites, sulfbismuthites, etc.)
C : Metal Sulfides, M: S = 1: 1 (and similar)
D : With Sn, Pb, Hg, etc.

Related to:

Galena Group. Clausthalite-Galena Series.

Members of Group:

Galena Group: Alabandite, Altaite, Clausthalite, Galena, Niningerite, Oldhamite 

Varieties:

None

Synonyms:

Clausthalie, ICSD 38294, Lerbachite, PDF 6-354, Selenbleiglanz, Tilkerodite, Zorgite

Crystal Data

Crystallography:

Monoclinic - Prismatic

Crystal Habit:

Commonly massive, also fine granular or foliated.

Twinning:

None

Physical Properties

Cleavage:

Good on {001}

Fracture:

Irregular/uneven, granular

Tenacity:

Brittle

Moh's Hardness:

2.5 - 3.0; Vickers: VHN₁₀₀=44-49 kg/mm²

Density:

7.8 - 8.22 (g/cm³)

Luminescence:

None

Radioactivity:

Not Radioactive

Optical Properties

Color:

Lead-gray, bluish; galena-white with a grayish tinge in reflected light

Transparency:

Opaque

Luster:

Metallic

Refractive Index:

R: (400) 63.4, (420) 63.0, (440) 61.8, (460) 60.1, (480) 58.4, (500) 56.7, (520) 55.3, (540) 54.0, (560) 52.7, (580) 51.6, (600) 50.7, (620) 49.9, (640) 49.4, (660) 48.8, (680) 48.4, (700) 48.2

Birefringence:

0.000 (opaque)

Dispersion:

None

Pleochroism:

None

Anisotropism:

Galena-white with a grayish tinge in reflected light

Occurances

Geological Setting:

Associated in low-sulfur hydrothermal deposits with other selenides, also in mercury deposits. Probably of secondary origin in some deposits.

Common Associations:

Tiemannite, Klockmannite, Berzelianite, Umangite, Gold, Stibiopalladinite, uraninite.

Common Impurities:

Hg, Co, Cu

Type Locality:

St Lorenz Mine, Burgstatt veins, Clausthal-Zellerfeld, Harz, Lower Saxony, Germany

Year Discovered:

1832

View mineral photos:

Clausthalite Mineral Photos and Locations

Unusual Gem Categories

Metallic Gems

More Information

Mindat.org
Webmineral.com

Clausthalite is a member of the Galena Group of minerals that also includes Alabandite, Altaite and Galena. Clausthalite is one of the most common selenide minerals. It is very similar to Galena because they have basically the same structure but Clausthalite has a greater density and lacks good crystals. It is opaque with a bright lead-gray color, metallic luster and a Mohs hardness of 2.5 - 3.0. Clausthalite is named after the discovery locality at Clausthal-Zellerfeld, Harz Mountains, Germany. The picture above shows a gem with veins of bright, metallic Clausthalite in Calcite matrix.

Clausthalite distribution: in Germany, from the Charlotte mine, Clausthal, 13 km south-southwest of Goslar [TL], Tilkerode, Lerbach, and Zorge, in the Harz Mountains, and at Schneeberg, Saxony. At Skrikerum, Sweden. From Hope’s Nose, Torquay, Devon, England. In the Czech Republic, at Bukov, near Tisnova; in the Petrovice uranium deposit, near Ždár; and the Predborice uranium deposit, near Krásna Hora. In the USA, in the Blue Range Wilderness Area, Greenlee County, Arizona; and at the Essex mine, Darwin, Inyo County, California. In the Goldfields district, Saskatchewan; in the Kidd Creek mine, near Timmins, and the Hemlo gold deposit, Thunder Bay district, Ontario, Canada. In Argentina, from the Sierra de Umango; in the Santa Brigida mine; at Tuminico, Sierra de Cacho; and from Los Llantenes, La Rioja Province, and from Cerro de Cacheuta, Mendoza Province. At the Pacajake mine, Hiaco, 24 km east-northeast of Colquechaca, Potosí, Bolivia. From El Sharana, Northern Territory, Australia. At Tsumeb, Namibia. Other minor occurrences are known.

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