PREFACE TO SEVENTH EDITION. 



SINCE the first edition was published, in the autumn of 

 1885, several important discoveries and openings up of 

 metal-producing districts in various parts of the world have 

 occurred, and references to these have now been added. 

 Of such, the gold fields of South Africa and Western 

 Australia are the most important ; and the circumstances 

 under which the precious metal has been found in the 

 conglomerates of the former have astonished many experts. 

 They certainly suggest an important lesson to the pro- 

 spector, viz. That it behoves him to explore a country 

 with a mind open to new impressions. If he does not do 

 so, for instance, in a large tract of land like West Australia, 

 where mineral wealth seems to have been bountifully dis- 

 tributed in so many districts, he will be apt to overlook 

 much that might be valuable. 



Opportunity has been taken to refer to Aluminium ores. 

 The metal has undoubtedly a great future before it ; the 

 discovery of a bed rich in aluminium ore is not by any 

 means to be despised. 



With regard to the Tables for the determination of a 

 mineral by noting the colour and lustre, and then the 

 streak, it should be borne in mind that, purposely, only a 

 limited number of minerals have been tabulated, and also 

 that the matter relating to the extraction of metal from 

 ores and the concentration of minerals is necessarily in a 

 very condensed form. 



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