Habit & Form
Cornish Minerals
About us

William Phillips in his book 'An Elementary Introduction to the knowledge of Mineralogy' third edition published in 1823 gave the following account of what he called Octahedral Arseniate of Copper, almost certainly Liroconite


There are several varieties of arseniate of copper, which differ somewhat in their chemical characters, but which are very readily distinguishable by their external forms.


Octahedral arseniate, Bournon. Linsenerz W. Cuivre arseniate primitif H. Lenticular Copper-ore J.

It is found of a bluish-white, sky-blue, and smalt-blue, also greenish-white and deep grass-green: it is translucent, or translucent only on the edges; it yields to mechanical division, though with difficulty, parallel to all the planes of an obtuse octahedron, of which the common base of the two pyramids is rectangular: the cross fracture is uneven with a vitreous lustre; it is scratched by fluor.  Its specific gravity is 2.88. It consists of 49 oxide of copper, 14 of arsenic acid,  and 35 of water.  Chenevix. Before the blow-pipe, it is converted to a black friable scoria, and by subsequent fusion with borax affords a bead of copper.

It has been found only in the veins passing through the adjoining mines, Huel Muttrell, Huel Gorland, and Huel Unity in Cornwall, associated with the following varieties;  also with red oxide of copper, copper pyrites, arseniate of iron, and the martial arseniate of copper.

Diagram of Octahedral Arseniate of Copper crystals by William Phillips, 1823

J.H.Collins in his book 'A Handbook to the Mineralogy of Cornwall and Devon' published in 1871 gave the following description of Liroconite

[Octahedral Arseniate of Copper. Lenticular Arseniate, &c. ]  Rhombic or oblique; in obtuse faintly striated double pyramids; crystals usually minute, but have been obtained formerly as much as one inch in length; sometimes in granular masses, but more rarely so than crystallized; sectile; fracture conchoidal or uneven; translucent; vitreous to resinous; sky-blue to verdigris-green; streak pale blue; H. 2-2.5; G. 2.8-3.0.

B., etc. In matrass gives off much water and turns dark green; on C alone deflagrates, fuses readily to a dark slag containing granules of copper; deposits a white incrustation on the charcoal at a considerale distance from the assay; with soda, after well roasting, yields a malleable bead of copper; easily soluble in HNO3; decomposed when in powder by solution of KHO3 leaving a black powder of oxide of copper.

Loc. Huel Muttrell, Huel Gorland, Huel Unity, Gwennap, many years since; Great Hewas United, and Gunnislake more recently, but not such fine specimens. It is also said to have occurred at Huel Providence, Lelant.

Obs. It occurred always associated with other arsenates of copper. Its beautiful colour is sufficient to distinguish it from them all.

Copyright (C) 2003-2008 David Aubrey-Jones.  All rights reserved.  No part of this Web site and its contents may be reproduced in any form without the written permission of the author.

[Liroconite] [Rarity] [Discovery] [Habit & Form] [Descriptions] [Locations] [Cornish Minerals] [Links] [About us]