53 



The analysis was made on the sample dried at 100° C. : — 



100-46 

 The alkalies consisted chiefly of potass, but contained also a 

 little soda. 



Experiments made with this clay proved it to be admirably 

 adapted to the manufacture of firebricks. Indeed, the experi- 

 mental bricks made with it resisted a high temperature better 

 than the imported Stourbridge or Newcastle bricks. 



Chalcopxrite 

 Prom the Moonta Mine. Massive specimens of the mineral, 

 with iridescent tarnish " Peacock copper ore," and the untar* 

 nished form, have been examined, but, as the results prove, 

 both specimens have the same composition, viz., that represented 

 by the formula Cu,S, PeS,, PeS. 



No. I. is the analysis of the untarnished form, and No. II. 

 that of the " Peacock ore." No. III. shows the theoretical 

 composition of copper pyrites, deduced from the formula given 

 above. 



The samples for analysis were broken up into small pieces, 

 and portions containing any particles of gangue rejected. 



Copper 



Iron 



Sulphur 



Insoluble silicious residue 



100-52 10015 100-00 



BOENITE. 



The composition of this mineral from different localities 

 varies somewhat — in some cases the proportion of copper to 

 iron is as high as 12 to 1, while in others it is as low as 3 to 1. 

 The specimen examined was from the Moonta Mine. It was 

 broken up small and carefully picked over, in order to exclude 

 any small portions of gangue, but, in consequence of the 

 intimate admixture of quartz (the gangue in this instance), the 

 separation was not so perfect as could have been desired. 



