1893.] NATURAL SCIENCES OF PHILADELPHIA. 197 



PYROPHYLLITE SLATES IN NORTHERN PENNSYLVANIA. 

 BY ABRAHAM MEYER. 



The following communication was read from Mr. Abraham Meyer 

 as part of the Proceedings of the Mineralogical and Geological 

 Section : 



The Pyrophyllite slates of Lycoming and Tioga Counties occur in 

 the Formation No. VIII, g. Chemung, and Formation No. IX 

 (Red), Catskill. 



The first exposure in the Chemung formation shows that these slates 

 are found where there has been an evident disturbance of the original 

 stratification with some infiltration of water, possibly steam, and the 

 measures at such points seem to have undergone a great change from 

 their usual conditions in having the coarser silica eliminated and the 

 softer homogeneous aluminous material with a small per cent, of very 

 finely divided silica remaining (generally) very evenly disseminated 

 throughout .the mass. This class was found near the rolls in the 

 Chemung measures, Tioga County (where the quartzes, etc., referred 

 to were found) it occurred in layers from one-half inch to two inches 

 in thickness, and resembled the Vermont and Deep River, N. C, 

 pencil slates, but did not retain its homogeneous nature for any 

 distance. Upon the measures approaching the disturbance in the 

 horizontal strata near the rolls, it became permeated with silica, 

 which also formed cylindrical and ovoid masses of silicious matter, 

 so as to cause it to undergo a complete change, unfitting it for the 

 commercial purposes for which a perfectly homogeneous aluminous 

 shale would be desirable. 



The second exposure was observed in the middle member of 

 Formation No. IX, Red and Gray Catskill, in Cogan House and 

 Pine Townships, Lycoming County, and both under similar condi- 

 tions but in varying quantities. In Cogan House Township the slate 

 was observed under the concretionary ferruginous limestone (corn- 

 stone of Old Red Sandstone series), in company with black shaly cop- 

 per ore and a mass of light gray shales mixed with silicious and 

 granitoid paste, the gray shales being sprinkled with a thin film and 

 specks of green and blue carbonate of copper (no copper-ore of com- 

 mercial value being observed). These slates were from one-fourth 

 to one inch thick, and were slightly more silicious than those of the 

 first exposure found, the whole thickness of deposit not exceed- 



