REPORT OF DEPARTMENT OF METALLURGY. 271 



Auriferous gravel, from California and South Carolina. 



Auriferous pyrite, from Virginia and Colorado. 



Telluride ores — compounds of gold with tellurium, from Colorado. 



Iridium. 

 Iridosmine, from California. 



Silver. 



Native silver with native copper, from the Lake Superior region. 



Xative silver on sulphide of copper, from Montana. 



Wire silver, from Nevada, Montana, Idaho, and New Mexico. 



Native silver and horn silver, in sandstone, from Utah. 



Horn silver, from Colorado, Utah, Nevada, and New Mexico. 



Ruby silver, from Nevada. 



Base ores carrying silver (milling ores), from Nevada, Utah, and 

 Montana. 



Argentiferous lead ores (smelting ores), from Colorado, Utah, and 

 Nevada. 



Tin. 



On account of recent discoveries and the general interest attaching 

 to tin the list of the localities of the occurrence of cassiterite, or the 

 biuoxide of tin, has been made as complete as possible, and includes 

 Maine, New Hampshire, Virginia, North Carolina, Alabama, Montana, 

 and the Black Hills of Dakota. The tin ore of San Jacinto, Cal., is 

 also shown. 



With the tin ores are shown bars of tin reduced from the New Hamp- 

 shire (1840), Virginia, Alabama, Montana, and California ores; also a 

 collection of Welsh tin plate. 



Antimony. 

 The sulphide ores, from Utah (with metal) and California. 



Quicksilver. 

 Cinnabar, from California. 



Lead. 



The sulphide ores, from Missouri. (For argentiferous lead ores, see 

 under Silver.) 



Copper. 



Native copper, from the Lake Superior region in Michigan, including — 

 water-worn or surface specimens; specimens of the mass copper, and 

 chips obtained in cutting up the masses in the mine, and specimens 

 showing the disseminated free copper in the rock, both amygdaloid and 

 conglomerate. To these are added specimens illustrating the dressing 

 • •f the ores. 



