Cyanotrichite

Locality: Hilarion area, Kamariza Mines (Kamareza Mines), Agios Konstantinos [St Constantine] (Kamariza), Lavrion District Mines, Lavrion District (Laurion; Laurium), Attikí Prefecture (Attica; Attika), Greece Field of View: 6 mm Copyright © Fritz Schreiber
Chemical Formula: Cu4Al2(SO4)(OH)12 · 2H2O
Locality: Moldava Noua (Moldawa, Új Moldova), Banat, Romania.
Name Origin: From the Greek, kyaneos, “blue” and triches, “hair,” hence, blue hair.

Cyanotrichite is a hydrous copper aluminium sulfate mineral with formula Cu4Al2(SO4)(OH)12 · 2H2O, also known as lettsomite. Cyanotrichite forms velvety radial acicular crystal aggregates of extremely fine fibers. It crystallizes in the orthorhombic system and forms translucent bright blue acicular crystal clusters or drusey coatings. The Mohs hardness is 2 and the specific gravity ranges from 2.74 to 2.95. Refractive indices are nα=1.588 nβ=1.617 nγ=1.655.

Occurrence and discovery

It is an oxidation product of primary copper mineralization in a weathering environment with abundant aluminium and sulfate. Associated minerals include brochantite, spangolite, chalcophyllite, olivenite, tyrolite, parnauite, azurite and malachite.

The main deposits are Cap la Garrone in the Var (France), Romania and Arizona (USA).

It was first described in 1839 from Moldova Nouă, Banat, Romania. The name is from Greek kyaneos for “blue” and triches for “hair” referring to the typical color and habit. Its earlier name, Lettsomite, is taken from the name of William Garrow Lettsom (1804–1887), co-author of the 1858 Manual of the Mineralogy of Great Britain and Ireland.

Physical Properties of Cyanotrichite

Cleavage: {???} Good
Color: Sky blue, Light blue, Dark blue.
Density: 2.74 – 2.95, Average = 2.84
Fracture: Uneven – Flat surfaces (not cleavage) fractured in an uneven pattern.
Hardness: 2 – Gypsum
Luminescence: Non-fluorescent.
Luster: Silky
Streak: pale blue

Photo

Locality: Grand View Mine (Last Chance Mine; No. 1 Pat claim 3591; No. 5 Pat claim 3592a; No. 4 Pat claim 3592a; Canyon Copper Mine; Grand Canyon Mine), Horseshoe Mesa, Grandview District, Coconino Co., Arizona, USA Dimensions: 3.8 cm x 3.7 cm x 1.2 cm “Courtesy of Rob Lavinsky, The Arkenstone, www.iRocks.com”
Locality: Grand View Mine (Last Chance Mine; No. 1 Pat claim 3591; No. 5 Pat claim 3592a; No. 4 Pat claim 3592a; Canyon Copper Mine; Grand Canyon Mine), Horseshoe Mesa, Grandview District, Coconino Co., Arizona, USA FOV: 20 x 17 mm Copyright © Michael C. Roarke
Locality: Hilarion area, Kamariza Mines (Kamareza Mines), Agios Konstantinos [St Constantine] (Kamariza), Lavrion District Mines, Lavrion District (Laurion; Laurium), Attikí Prefecture (Attica; Attika), Greece Field of View: 5 mm Copyright © Fritz Schreiber
Locality: Grand View Mine (Last Chance Mine; No. 1 Pat claim 3591; No. 5 Pat claim 3592a; No. 4 Pat claim 3592a; Canyon Copper Mine; Grand Canyon Mine), Horseshoe Mesa, Grandview District, Coconino Co., Arizona, USA FOV: 5mm. Copyright © Michael Clin
SHARE