NEIGHBOURHOOD OF CORK. 



89 



These pieces resemble the finest kind of slate-clay 

 first mentioned; only they are of a darker co- 

 lour, and rather harder. Its structure in the great 

 is irregular slaty. It abounds in natural rents, and 

 short contemporaneous veins and nodules of quartz. 



There is another variety which approaches to thick 

 slaty in its fracture, and contains a few scales of mica. 

 In this are imbedded numerous reed-like films of a 

 dark colour, and so closely resembling some of the 

 varieties of sandstone, belonging to the independent 

 coal formation, as not to be distinguished from 

 them in hand specimens. The surface of these 

 reed-like films exhibits rather indistinctly the ap- 

 pearance of vegetable impressions. The resemblance, 

 however, to some of the impressions on the sandstone 

 of our coal-fields was so close, that I was disposed, 

 without further evidence, to assign to them a vege- 

 table origin. A more minute examination enabled 

 me to decide the question. 



The surface of these films was often shining, 

 and the black matter, ignited with nitre, proved to 

 be glance-coal. A more diligent search, led me to 

 discover in the rubbish of a quarry, a large cylinder, 

 upwards of eighteen inches in diameter, consisting 

 of glance-coal, iron-pyrites and calcareous spar. 

 Upon breaking the mass, it was easy to discover 

 its woody texture, by the fibres of the pyrites, and 

 the concentric circles of which it consisted. When 

 fresh broken, the pyrites exhibited its usual colour ; 

 but after exposure for a few days, it changed to 



