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The Mineral cyanotrichite

Cyanotrichite Cavity

Cyanotrichite is an attractive blue mineral with very characteristic radiating needle aggregates. It is a fragile mineral, and handling should be avoided, for even a slight touch can damage a crystal grouping. Cyanotrichite crystals will rub off and leave a blue residue of tiny crystals on a surface if handled.

The name of Cyanotrichite is derived from the Greek terms "kyanos", or blue, and "triches", meaning hair, in reference to its hair-like habits of blue crystals.

Chemical Formula

Cu₄Al₂SO₄(OH)₁₂ · 2H₂O

Color

Bright blue

Crystal System

Orthorhombic

Properties

Streak
Light blue

Hardness
1 - 3

Transparency
Translucent

Specific Gravity
2.7 - 2.8

Luster
Silky

Cleavage
None

Fracture
Splintery

Tenacity
Brittle

Crystal Habits

As scattered groups of radiating or acicular crystals. Also in ball-like aggregates of tiny, slender crystals, as plush, wool-like needle groupings, as crusty groupings of tiny needles, and in botryoidal crystal groups.

Additional Information

Composition
Basic hydrous copper aluminum sulfate

In Group
Sulfates; Hydrous Sulfates

Striking Features
Crystal aggregates and bright blue color

Environment
As a secondary mineral found in the oxidation zone of copper deposits.

Rock Type
Sedimentary, Metamorphic

Other Names

	Lettsomite
	Velvet Copper Ore

Varieties

Carbonatecyanotrichite

- A carbonate-rich variety of Cyanotrichite, where the sulfate radical (SO₄) is partially replaced by a carbonate radical (CO₂). Its chemical formula is Cu₄Al₂(CO3,SO4)(OH)₁₂ · 2H2O. Carbonatecyanotrichite is technically not really a variety since it is scientifically recognized as as a distinct mineral species, though it is identical to Cyanotrichite and virtually indistinguishable.

Uses

Cyanotrichite is an uncommon copper mineral, and is a very minor copper ore. It is popular as a micromount mineral.

Noteworthy Localities

European localities for Cyanotrichite include Cap Garonne and Salsigne, France; Wheal Basset, Cornwall, England; and Lavrion, Greece. One of the best producers of this mineral is in the Vieja Mine in Potrerillos, Chanaral Province, Chile. Good Cyanotrichite also comes from Qinglong, Guizhou Province, China.

In the U.S., Cyanotrichite has several good localities in Arizona, specifically the Grandview Mine near the Grand Canyon, in Concino Co.; the Copper Queen Mine in Bisbee, Cochise Co.; and the Maid of Sunshine Mine, Cortland, Cochise Co. Cyanotrichite also comes from the American Eagle Mine in the Tintic District in Juab Co., Utah; the Peacock Mine, Lemhi Co., Idaho; and the Majuba Hill mine, Pershing Co., Nevada.