10 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 7t 



The recognition of the crystal form of a "ruby silver" mineral 

 may be of importance in identifying the mineral and consequently 

 in estimating the probable silver content of the ore. The crystals of 

 miargyrite (36.9 per cent silver) are readily distinguished from those 

 of pyrargyrite (59.9 per cent silver), proustite (65.4 per cent silver), 

 and polybasite (75.6 per cent silver). All of these have a red streak 

 and pass under the name ruby silver. 



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