310 



MB. E. W. BISWET OS SOME SUPPOSED 



pois when whole. By the kindness of my friend, Dr. 

 Robert Angus Smith, I am enabled to give an analysis of 

 it, which is as follows : — 



Silica 96-463 



Alumina 2578 



Protoxide of Irou -644 



Lime '161 



99-846 

 THE PATRICROFT STONE. 



This was found by Mr. John Smith, in the colliery of 

 Messrs. John Lancaster and Co., at Patricroft, near Man- 

 chester, in the 4-feet seam, at a depth of 440 yards from the 

 surface, about the year 1845. It is composed of a crystal- 

 line quartzose stone of a darker gray than the specimen last 

 described, and having very small black spots dispersed 

 through its mass. The outside is partly smooth and partly 

 irregular, of a shining black polish on the surface, but 

 scarcely penetrating at all into the body of the stone. Marks 

 of slickenside are seen on all parts of it, with several patches 

 of sulphuret of iron. 



Fig. 2. 



Its form (see fig. 2) is that of 

 an irregular pyramid, having 

 ,,. mM ^ \ most of its angles rounded off. 

 ^^ShII^HI JmiM "^^^^ greatest length is 7 inches, 

 and the breadth 4 inches. It 

 weighs 6^ lbs. avoirdupois, and 

 has a specific gravity about 

 2*60. Dr. Smith's analysis of it is as follows : — 



Silica 96-050 



Alumina 2-529 



Protoxide of Iron "709 



Lime '525 



Magnesia '124 



99-937 



iiSiS' 



