Liroconite is a complex mineral: Hydrated copper aluminium arsenate hydroxide, with the formula Cu₂ Al As O₄�4(H₂O). It is a vitreous

monoclinic In crystallography, the monoclinic crystal system is one of the seven crystal systems. A crystal system is described by three vectors. In the monoclinic system, the crystal is described by vectors of unequal lengths, as in the orthorhombic ...

mineral, colored bright blue to green, often associated with

malachite Malachite is a copper carbonate hydroxide mineral, with the formula Cu2CO3(OH)2. This opaque, green-banded mineral crystallizes in the monoclinic crystal system, and most often forms botryoidal, fibrous, or stalagmitic masses, in fracture ...

azurite Azurite is a soft, deep-blue copper mineral produced by weathering of copper ore deposits. During the early 19th century, it was also known as chessylite, after the type locality at Chessy-les-Mines near Lyon, France. The mineral, a basic car ...

olivenite Olivenite is a copper arsenate mineral, formula Cu2 As O4O H. It crystallizes in the monoclinic system (pseudo-orthorhombic), and is sometimes found in small brilliant crystals of simple prismatic habit terminated by domal faces. More commo ...

, and clinoclase. It is quite soft, with a

Mohs hardness The Mohs scale of mineral hardness () is a qualitative ordinal scale, from 1 to 10, characterizing scratch resistance of various minerals through the ability of harder material to scratch softer material. The scale was introduced in 1812 by ...

of 2 - 2.5, and has a

specific gravity Relative density, or specific gravity, is the ratio of the density (mass of a unit volume) of a substance to the density of a given reference material. Specific gravity for liquids is nearly always measured with respect to water at its dens ...

of 2.9 - 3.0. Liroconite-Clinoclase-120699

It was first identified in 1825 in the tin and copper mines of Devon and

Cornwall, England Cornwall (; kw, Kernow ) is a historic county and ceremonial county in South West England. It is recognised as one of the Celtic nations, and is the homeland of the Cornish people. Cornwall is bordered to the north and west by the Atlantic ...

. Although it remains quite rare it has subsequently been identified in a variety of locations including

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and

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. The type locality for liroconite is Wheal Gorland in

St Day St Day ( kw, Sen Day) is a civil parish and village in Cornwall, England, United Kingdom. It is situated between the village of Chacewater and the town of Redruth. The electoral ward St Day and Lanner had a population at the 2011 census of 4,473 ...

Cornwall Cornwall (; kw, Kernow ) is a Historic counties of England, historic county and Ceremonial counties of England, ceremonial county in South West England. It is recognised as one of the Celtic nations, and is the homeland of the Cornish people ...

in the United Kingdom. The largest crystal specimen on public display is in the

Royal Cornwall Museum The Royal Cornwall Museum in Truro holds an extensive mineral collection rooted in Cornwall's mining and engineering heritage (including much of the mineral collection of Philip Rashleigh (1729-1811), Philip Rashleigh). The county's artistic her ...

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. It occurs as a secondary mineral in copper deposits in association with

, chalcophyllite, clinoclase, cornwallite, strashimirite,

cuprite Cuprite is an oxide mineral composed of copper(I) oxide Cu2O, and is a minor ore of copper. Its dark crystals with red internal reflections are in the isometric system hexoctahedral class, appearing as cubic, octahedral, or dodecahedral forms, o ...

and

limonite Limonite () is an iron ore consisting of a mixture of hydrated iron(III) oxide-hydroxides in varying composition. The generic formula is frequently written as FeO(OH)·H2O, although this is not entirely accurate as the ratio of oxide to hydroxide ...

Structure

Liroconite crystallizes in the

monoclinic crystal system In crystallography, the monoclinic crystal system is one of the seven crystal systems. A crystal system is described by three vectors. In the monoclinic system, the crystal is described by vectors of unequal lengths, as in the orthorhombic ...

. The

crystal structure In crystallography, crystal structure is a description of the ordered arrangement of atoms, ions or molecules in a crystalline material. Ordered structures occur from the intrinsic nature of the constituent particles to form symmetric pattern ...

consists of a framework of AsO₄

tetrahedra In geometry, a tetrahedron (plural: tetrahedra or tetrahedrons), also known as a triangular pyramid, is a polyhedron composed of four triangular faces, six straight edges, and four vertex corners. The tetrahedron is the simplest of all th ...

, Jahn-Teller-distorted uO₂(OH)₂(H₂O)₂ octahedra and lO₂(OH)₄octahedra. Liroconite-unit-cell-3D-bs-N17-M25

References

Copper(II) minerals Arsenate minerals Monoclinic minerals Minerals in space group 15 {{mineral-stub

Structure

See also

References