jia5 CtEOLOGV OF THE VICINITY OF JJUBtlfT* 



of these writh the specimens from Douce, the identity ©f 

 Karsten's fossil with andalusite is ascertuioed. I have not 

 found however, that this claim to the first detection of it has 

 been mentioned by subsequent writers: although his opinion 

 -with respect to its affinity to felspar accords with that 

 which Haiiy is disposed to adopt. Tableau connparatif, &c. 

 p. 217. 



Tothis species 13 aUo to be referred tk mineral which occurs 

 in great abundance at Killiney in the county of Dublin, 

 first observed there by Dr. Blake, and for some time consi- 

 dered as belonging to a nondescript species. It is most re- 

 i. markable on the shore at the southern extremity of tlie cliff 



x»nder the obelisk bill, where it appears thickly on the sur- 

 face of beds of mica slate ; and it seems to abound also im- 

 . bedded in the substance of that rock,^lthough less distinctly 

 •visible until it has been exposed to decomposition, being 

 less affected by exposure than the rock in which it is con- 

 tained. 



The andalusite, when thps brought to view, appears ge- 

 , nerally in slender prismatic crystalline pieces rounded at the 

 angles, seldom sharp, promiscuously aggregated, sometimes 

 in a stellular form, ^lid of a grayish-black colour, remark- 

 ably contrasted with Xhp lustre and light colour of the mica- 

 ceous substance in which they appear. But in fresher 

 pieces, the form, colour, cleavage, and other characters of 

 this mineral are distinct ; and I have observed an approach 

 to the peculiar appearances, which it presents at this place, 

 in some Spanish specimens, where the crystalline shootis had " 

 assumed a scapiform arrangement. 

 Crystals of ^' ^^^ andalusite of Douce mountain is accompanied. 



Indurated as Ijas been mentioned, by a crystallized mineral, the cba- 

 . racteYs of which have much affinity to those of indurated 

 talc ; and which is placed under that denomination in the 

 collection of Dublin College (Nos. 405, 6, 7) ; and a speci- 

 men of the same kind, stated to be from Glendalagh in the 

 county of Wicklow, was found in the same collection 

 (No. 404.) 



The crystals are rhomboldal prisms, of which the length 

 is in some instances more than twice the breadth, but no 

 •cumination is observable. They are easily cut by the 



knife. 



talc? 



