338 



C\ H. Warren — Miner alogical Notes. 



The reniform masses, as is usual with native arsenic, are 

 black in color, or gray on freshly broken surfaces, and consist 

 of many thin concentric layers. While no distinct crystallo- 

 graphic outlines can be seen, each layer appears to be made up 

 of semi-crystalline arsenic having a prismatic structure nor- 

 mal to the surface. What appear to be extremely small pris- 

 matic crystals have been noticed in a single instance. The 

 masses are considerably fissured and the openings thus formed 

 have been largely filled with later minerals, which also appear 

 abundantly on the surface and in the solution cavities men- 

 tioned beyond. Of these minerals quartz and calcite are the 

 most abundant, the former as small but well-terminated pris- 

 matic crystals, the latter in a slightly discolored, massive 

 crystalline form. 



1 



Fig. 2. Top view. 



The arsenic has been attacked to a considerable extent by 

 some solvent. This has removed portions of the arsenic by 

 attacking first the edges of the layers, where these were 

 exposed by a fissure. It then encroached gradually on the 

 substance of the layers by dissolving out narrow channels vary- 

 ing in width from that of a line to O'S""". These channels 

 »amify into networks, which give rise to an appearance sug- 

 gesting that of a finely sun-cracked piece of mud. This 



