Dec. 1861.] Geuloyy of the Neilyherries. 233 



(d.) Green Jasper, passing into a brown variety, 

 (e ) Siliceous Schist passing into Hornblende Schist, 

 ( /.) Ferruginous Clay (A in Macullock's Synopsis of clays,) 

 (y.) The above Clay converted into Porcelain Jasper, 

 (h.) Small Crystals of Sahlite diffused between the joints of 

 an altered Schist. 



(«.) Traps that have wrought the above mutations, comprising 

 compact Hornblende, Hornstone Trap, and Porphyritic Trap con- 

 taining green earth in Crystals of Felspar. 



(a.) The Siliceous Schist has generally a dark greyish color, 

 occasionally almost white. It is a concretion of thin lamina? of 

 quartz, and is very hard except on the weathered surfaces. 



(5.) The Lydian stone is nothing more than the Schist in a 

 compact state and of darker hue. This is the touchstone of the 

 Goldsmiths. 



(c.) The Siliceous jasper is the Schist in an altered state, hav- 

 ing a dirty white base banded with yellow, green, and brown. 

 Polished, this stone would be an acquisition to the Mineralogical 

 cabinet. 



(d.) The next jasper possesses a fine green color traversed by 

 stripes of a darker complexion. 



Probably it owes its color to the green earth suspended in the 

 contiguous Trap. This jasper is not quite so hard as the preced- 

 ing variety, its edges are translucent, the fracture is somewhat 

 conchoidal. 



It is rare. It passes into a light brown variety with white stripes 

 (e.) With regard to the Hornblende Schist, it would seem that 

 the Trap has parted with a portion of its Hornblende, and by in- 

 sinuating it between the leaves of the Schist converted it into a 

 kind of Hornblende slate. 



(/.) Ferruginous clay next comes under our notice. 



This indurated clay or wakke, fractures into rectangular and 

 doubly oblique prisms. It has a yellow streak, and is of considera- 

 ble specific gravity owing to the iron impregnating it, which soils 

 the fingers. Where this clay has come in immediate contact with 

 the Trap it has been altered into a Porcelain jasper (g) of a light 



