1882.] OJiJ [Genth. 



^3. Another alteration, shown by many of the crystals, is that into a 

 micaceous, chloritic mineral. It either forms a coating parallel with the 

 octahedral planes or penetrates the crystals irregularis^ in every direction. 



It has a white, grayish- or greenish-white color, is sectile and very little 

 elastic. On ignition it does not exfoliate, but turns silver-white. The 

 ignited mineral is easily decomposed by sulphuric acid. 0.2747 grms. 

 although not quite, but nearly pure, was all that I could obtain for 

 analysis, from which 0.0140 grms. insoluble in sulphuric acid and, sub- 

 sequently, in sodium hydrate was deducted as impurity. The results 



97.18 100.00 



These results show the mineral to belong to the chlorite group, closely 

 agreeing witli the formula H^o [FeTr^^gMg+ff jj^ Alg Si,, Ogg, for which I 

 give calculated percentage above. It must remain undecided whether 

 or not this is a new species, until larger quantities of pure material can 

 be obtained for a fuller investigation. 



VL Butile and Zircon from the Itacolumite of Edge Hill, Bucks 

 County, Pa. 



In the examination of a series of "Edge Hill rocks " which, according 

 to Mr. Charles E. Hall (Report C6., of the 2d Geological Survey of Penn- 

 sylvania), are Potsdam sandstone, I have made a few observations which 

 should be placed on record. 



The rocks are generally thinly laminated quartzites which contain j-el- 

 lowish-white scales of muscovite in larger or smaller quantity, and are 

 identical in appearance with the large mass of the "itacolumite " rocks of 

 the Southern States, which do not show any flexibility. 



Especially in Neeley's Quarry, but also in smaller quantitj' in many 

 others, the rock contains exceedingly minute, yellowish, orange or brown- 

 ish-yellow grains, they are smaller than 0.25"™. By powdering and levi- 

 gation I have obtained a considerable quantity of the same. 



Under the microscope they appear as irregular, sharp, angular fragments, 

 showing now and then a very smooth plane, but no distinct crystalline 

 form. They have a honey -yellow color. B. B. they gave the reaction of 

 titanic oxide, and a very minute trace of tin. , 



