Plancheite
Current inventory:  0 gems
 

  
Plancheite was named after French explorer, J. Planche, who supplied samples to Alfred Lacroix from Mindouli who first described the mineral.

Discovered in 1908; IMA status: Valid (pre-IMA; Grandfathered)

Chemistry

Chemical Formula:

Cu₈Si₈O₂₂(OH)₄ • 2H₂O

Hydrated Copper Silicate Hydroxide

Molecular Weight:

1,171.08 gm

Composition:

Copper

43.41 %

Cu

54.34 %

CuO

Silicon

19.19 %

Si

41.05 %

SiO₂

Hydrogen

0.52 %

H

4.62 %

H₂O

Oxygen

36.89 %

O

100.00 %

100.00 %

= TOTAL OXIDE

Classification

Mineral Classification:

Silicates (Germanates)

Strunz 8th Ed. ID:

8/F.05-10

Nickel-Strunz 10th Ed. ID:

9.DB.35

9 : SILICATES (Germanates)
D : Inosilicates
B : Inosilicates with 2-periodic single chains, Si₂O₆; Pyroxene-related minerals

Related to:

n/a

Varieties:

None

Synonyms:

Bisbeeite, ICSD 100073, Katangaite, Katangite, PDF 29-576

Crystal Data

Crystallography:

Orthorhombic - Dipyramidal

Crystal Habit:

Crystals fibrous by extension on [001], striated; commonly as compact radial aggregates. 

Twinning:

None

Physical Properties

Cleavage:

None

Fracture:

Unknown; crystals are too small to observe fractures

Tenacity:

Brittle, fibrous

Moh's Hardness:

6.0

Density:

3.65 - 3.80 (g/cm³)

Luminescence:

None

Radioactivity:

Not Radioactive

Optical Properties

Color:

Pale blue to deep blue, pale greenish blue

Transparency:

Translucent

Luster:

Silky

Refractive Index:

1.645 - 1.715  Biaxial ( + )

Birefringence:

0.070

Dispersion:

Relatively strong

Pleochroism:

Visible, marked; X= pale blue, Y=Z= blue

Occurances

Geological Setting:

A rare secondary mineral in the oxidized portion of copper deposits.

Common Associations:

Chrysocolla, Dioptase, Malachite, Conichalcite, Tenorite

Common Impurities:

n/a

Type Locality:

Sanda Mine, Mindouli, Mindouli District, Pool Department, Republic of Congo (Brazzaville)

Year Discovered:

1908

View mineral photos:

Plancheite Mineral Photos and Locations

More Information

Mindat.org
Webmineral.com

Plancheite was named after French explorer, J. Planche, who supplied samples to Alfred Lacroix from Mindouli who first described the mineral. The samples were found by Planche at the Sanda Mine, Mindouli, Pool Departmant, Republic of Congo. Plancheite is a rare secondary mineral formed in the oxidation zone of copper deposits. It is a hydrated copper silicate mineral and is closely related to Shattuckite in structure and appearance. The two minerals are often confused. Like so many other secondary copper minerals, Plancheite is colorful, attractive and has interesting crystal habits that are typically fibrous, compact radial aggregates. It is often found associated with other colorful secondary copper minerals such as Chrysocolla, Conichalcite, Dioptase, Malachite, Shattuckite and Brochantite.

Distribution: From Mindouli, Renéville, and Tshiniama, Congo Republic. In Congo (Zaire), fine material from Tantara, Mindigi, and M'sesa, near Kambove, Katanga (Shaba) Province. From Tsumeb, Guchab, and Okatumba, about 80 km east of Windhoek, Namibia. In England, at the Driggith mine, Caldbeck Fells, Cumbria; the Gunheath china clay pit, St. Austell, Cornwall; and the Engine vein, Alderley Edge, Cheshire. In the USA, in Arizona, from the Table Mountain mine, Galiuro Mountains, and the Azurite mine, Tortolita Mountains, Pinal County; in the Bighorn district, south of Aguila, Maricopa County; in the Harquehala Mountains, Yuma County; and elsewhere. In Michigan, from the Algomah mine, Ontonagon County. In the Kurokawa mine, Gifu Prefecture, and the Kisanmori mine, Akita Prefecture, Japan. From La Rioja, Argentina.
 

  
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