Carrollite
Current inventory:  0 gems
 

  
Carrollite is named after the type locality in Carroll County, Maryland, USA.

Discovered in 1852;   IMA status: Valid (pre-IMA; Grandfathered)

Chemistry

Chemical Formula:

Cu(Co,Ni)₂S₄

Copper Cobalt Nickel Sulfide

Molecular Weight:

309.55 gm

Composition:

Cobalt

28.56 %

Co

Copper

20.53 %

Cu

Nickel

9.48 %

Ni

Sulfur

41.43 %

O

100.00 %

Classification

Mineral Classification:

Sulphides

Strunz 8th Ed. ID:

2/D.01-40

Nickel-Strunz 10th Ed. ID:

2.DA.05

2 : SULFIDES and SULFOSALTS (sulfides, selenides, tellurides; arsenides, antimonides, bismuthides; sulfarsenites, sulfantimonites, sulfbismuthites, etc.)
D : Metal Sulfides, M: S = 3 :4 and 2:3
A : M:S = 3:4

Related to:

Thiospinel Group. Isostructural with Linnaeite.

Members of Group:

Thiospinel Group: Bornhardtite, Cadmoindite, Carrollite, Cuproiridsite, Cuprorhodsite, Daubréelite, Ferrorhodsite, Fletcherite, Florensovite, Greigite, Indite, Kalininite, Linnaeite, Malanite, Polydymite, Siegenite, Trüstedtite, Tyrrellite, Violarite, Xingzhongite

Varieties:

None

Synonyms:

Carrolite, Corrolite, Sychnodymite

Crystal Data

Crystallography:

Isometric - Hexoctahedral

Crystal Habit:

Octahedral crystals, to 10 cm; commonly massive, disseminated granular to compact.

Twinning:

On {111}; may show polysynthetic twin lamellae

Physical Properties

Cleavage:

Imperfect on {001}

Fracture:

Irregular/Uneven to Sub-Conchoidal

Tenacity:

Brittle

Moh's Hardness:

4.5 - 5.5; VHN = 507–586 (100 g load)

Density:

4.50 - 4.80 (g/cm³)

Luminescence:

None

Radioactivity:

Not Radioactive

Optical Properties

Color:

Pale gray to steel-gray, tarnishing easily to copper-red or violet-gray

Transparency:

Opaque

Luster:

Metallic

Refractive Index:

Isotropic; R: (400) 41.4, (420) 41.5, (440) 41.6, (460) 41.8, (480) 42.0, (500) 42.3, (520) 42.6, (540) 42.9, (560) 43.1, (580) 43.3, (600) 43.5, (620) 43.9, (640) 44.3, (660) 44.7, (680) 45.0, (700) 45.3

Birefringence:

0.00; Isotropic

Dispersion:

None

Pleochroism:

None

Occurances

Geological Setting:

In hydrothermal vein deposits.

Common Associations:

Tetrahedrite, Linnaeite, Siegenite, Polydymite, Chalcopyrite, Bornite, Digenite, Djurleite, Chacocite, Pyrrhotite, Pyrite, Sphalerite, Millerite, Gersdorffite, Ullmannite, Cobaltoan Calcite

Common Impurities:

None

Type Locality:

Patapsco mine (Patapsco Mines; Finksburg Mine; Wildesen Mine; Orchard Mine), Finksburg, Carroll Co., Maryland, USA

Year Discovered:

1852

View mineral photos:

Carrolite Mineral Photos and Locations

More Information

Mindat.org
Webmineral.com

Carrollite is a rare sulfide of copper and cobalt rarely seen faceted. It is opaque, metallic black and very dense. It is a gem for "black gem" collectors.

Distribution of Carrollite is In the USA, from Carroll County, Maryland, in the Patapsco mine, Finksburg [TL], and the Mineral Hill mine, Sykesville. At Boleo, Baja California, Mexico. In the Carrizal Alto copper district, Atacama, Chile. From near Chernomorets, Burgas, Bulgaria. At Vysna Boca, Nizke Tatry Mountains, Slovakia. In the Kohlenbach mine, near Eiserfeld, and throughout the Siegerland district, North Rhine-Westphalia, Germany. From Gladhammar, Kalmar, Sweden. At Tsumeb, Namibia. Large crystals from Kambove, and in the Kamoto and Musonoi mines, near Kolwezi, Katanga Province, Congo (Shaba Province, Zaire). From the Rokana mine, Kitwe, Zambia. At the Madziwa (Dry Nickel) mine, Bindura, and Shamva, Zimbabwe. In the Sazare mine, Ehime Prefecture, and the Shirataki mine, Kochi Prefecture, Japan. At the Hol Kol Au–Cu mine, about 75 km southeast of Pyongyang, Suan Co., North Korea. From Kambalda, 56 km south of Kalgoorlie, Western Australia. A substantial number of other minor occurrences are known.
 

  
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