196 PROCEEDINGS OF THE ACADEMY OF [1893. 



black crystals are much harder than common quartz, and have 

 centers of prismatic colors, which by reflected light assume an 

 asteriated form. 



7. Associated also with the tabular quartz is a brownish-red 

 ferruginous quartz one piece of which showed crystals of intense 

 black color, except two zones at the base, which showed prismatic 

 colors, and under the microscope the asterism. The point of this 

 crystal was extremely hard. 



8. On a line with the rolls, but 125 feet above them topographic- 

 ally, was ferruginous calcite and massive quartz with rough quartz 

 crystals, the surfaces pitted and filled with clay. The massive 

 quartz breaks very readily into angular fragments, the surfaces 

 coated with dendrites. Some of the crystals are coated with druses 

 of black color and metallic lustre, some crystalline, some quite rough. 

 Under the microscope some of these show crystalline forms of light 

 straw color resembling millerite. 



My theory of the formation of these rolls is that a subterranean 

 force acting over an oval area ten or twelve miles by four culmin- 

 ated in making them; the zone of most active force being about 

 two and a half miles in diameter. That steam and water carrying 

 carbon, lime, iron, etc., penetrated the crevices, formed and deposited 

 the minerals and crystals; unfortunately for mining interests this 

 action was scattered over a considerable extent of country whereas 

 had it been confined to a narrow vein, a valuable mine might have 

 been the result. 



