MINERALS FROM LAKF. SUPERIOR. 411 



shbre of the bay, about two years ago. The vein in question averages 

 about five or six inclies in width, and is nearly vertical. A thin layer 

 of colourless quartz lines the walls on each side. This is followed by 

 about half-an-inch or rather more of Iron Pyrites, possessing a radiated 

 structure, but crystallizing on its inner surface in combinations of the 

 cube and octahedron. To this succeeds another band of white, crys- 

 tallized quartz ; and the middle of the vein is filled with black and 

 highly lustrous anthracite. The vein thus offers, though of small 

 size, a fine example of banded or riband structure, shewing, in passing 

 from one wall to the other : 1, quartz ; 2, iron pyrites ; 3, quartz ; 4, 

 anthracite ; 5, quartz ; 6, iron pyrites ; and 7, quartz. Here and 

 there, a thin coating of anthracitic matter occurs also on the surface of 

 the pyrites, or runs through the latter, dividing it into two or more 

 layers. So far as my observations go, all the large mineral veins ot 

 this district exhibit, on the other hand, a brecciated structure, with 

 very subordinate or irregular indications of banding. 



The anthracite from this vein possesses the following characters : — 

 Colour, jet-black, with high lustre ; streak, greyish -black. Very hrit- 

 tle. Fracture, more or less eonchoidal. H=2*2o — 2 "5. Sp. gr. 

 (as determined by a light sp. gr. bottle)=l-43. Before the blowpipe 

 it cracks slightly and loses its surface lustre, but exhibits no further 

 change. Heated in a small flask or bulb-tube, it gives off a little 

 moisture, but without any accompanying trace of bituminous matter. 

 In powder, in a thin platinum capsule, it burns completely away, but 

 a long-continued ignition over a Bunsen's burner or double-current 

 lamp is necessary to effect this. Carefully picked fragments do not 

 leave a trace of ash : a peculiarity which must not be lost sight of, in 

 attempted explanations of the origin of anthracitic matter in this appa- 

 rently abnormal position. 



Two assays gave the following results : 



Moisture 2-08... 2*23 



Additional Iqss by ignition inclosed vessel... S'56... 3*62 



Ash 0-00... 0-00 



Fixed carbon, by difference 94*36. ..94* 15 



