Geology and Natural History. 307 
posterior formation and identical in the mode of its formation with 
ordinary concretionary veins. Similar evidences, though less 
the angles and incrusted with metallic sulphids. Similar speci- 
mens occur in the clearly transverse lode of Ore Knob. In the 
80 much used in Maine and New Hampshire. A stone of this kind 
s Ses in some varieties of this ore, which, in other cases, ap- 
proaches more nearly to erubescite or calcopyrite mm Its composi- 
ome masses of these ores hold grams of native copper or 
