MR. CHARLES A. BURGHARDT ON COPPER-ORES. 171 



XXII. On the Origin of some Ores of Copper. — Part I. 

 By Charles A. Burghardt, Ph.D., The Owens College. 



Read November Z7tb, 1877. 



To endeavour to trace the various ores of copper to one 

 fundamental source, and to study the relatiouships pro- 

 bably existing between the copper compound and its ac- 

 companying minerals, has appeared to me a subject of 

 great interest ; in fact it has engaged my attention for 

 some time. The commonest occurring ore of copper is 

 undoubtedly cuprite (Cu^O) , either independently or more 

 often associated with malachite, azurite, brown iron-ore, 

 and native copper. Scarcely a specimen of copper-ore can 

 be obtained (with the exception of the sulphides) which 

 does not exhibit more or less cuprite in intimate inter- 

 mixture with the other ore ; whence it must be inferred 

 that all, or almost all the ores of copper have been formed 

 by aqueous and not by plutonic action, as cuprous oxide is 

 undoubtedly prepared with greater facility by the wet 

 method (that is, from cuprous or cupric solutions) at a 

 comparatively low temperature than by the dry method at 

 a very high temperature. I will briefly state in which way 

 cuprite (that is, the crystallized cuprous oxide) has been 

 obtained by different authors, first by the dry method, and 

 secondly by the wet method. 



Preparation of Cuprite. 



Dry Methods of Preparation of Cuprite. 

 I . A mixture of 24 parts of cupric sulphate and 29 parts 



