Mr. J. Napier on Copper Smelting. 53 



Green Carbonate of Copper is easily distinguished by its rich 

 grass-green colour ; it has a considerable lustre, is harder than 

 the blue carbonate, and the crystals are generally fibrous. A 

 variety of this mineral, which is generally found in nodules formed 

 of a series of concentric layers, is known as malachite, which, when 

 cut and pohshed, is of great beauty, and is consequently used 

 for ornamental purposes. The Russian mines were long famed 

 for their malachite ore, but it is now found in great quantities in 

 some of the Australian mines. The difference of composition 

 of the blue and green carbonate of copper is, that the one con- 

 tains more chemically combined water than the other, which is no 

 doubt the cause of the difference in colour. The following is 

 their composition when pure : — 



Blue. Green. 



'&A')mt - Copper oxide ... 70 70-5 



Carbonic acid ... 24 18'0 



Water _6 U'S 



100 1000 



■ Per the composition of the various carbonate ores, we refer to 

 the table of Burra Burra ores. 



Sulphuret of Copper. — This is a very abundant ore, and has 

 a great many varieties ; the colour is lead-gray ; it is vitreous in 

 appearance, and compact, often assuming a blue tint upon the 

 surface ; it is very heavy, and easily distinguished. As an ore, 

 it is generally associated with iron and silica ; it is an abundant 

 ore in ChUi. A great mass of this ore, which was exhibited in 

 the Great Exhibition, gave — 



Copper .... 55 

 Sulphur ... 35 



Iron 14 



Silica .... 6 

 100 

 It is often found richer than this, but this analysis may be 

 taken as the average composition. 



Gray Copper Ore is named from its having a steel-gray colour. 

 It is a veiy common ore of coppci", and is the principal mineral 

 found in some of the Cornish mines. This mineral is very variable 

 in its composition, scai'cely two locahties giving the same. The 

 following analyses will illustrate this variety : — 



981 99-6 100-0 



