562 



MINERALOGY OF THE REDHEAD. 



Others ckystone or compact felspar. It often as- 

 sumes a homogeneous aspect, and passes into mas- 

 sive compact felspar, felspar-porphyry, or por- 

 phyritic-slaty-felspar. In other cases, the felspar 

 passes into clinkstone, basalt, and greenstone, con- 

 taining small specks of diallage. In this assem- 

 blage, I observed several partial beds of fine- 

 grained sandstone, of a grey, greenish, or brown 

 colour. In some places, these occur in connected 

 masses, upwards of a hundred yards in length and 

 breadth, while they do not exceed a foot in thickness. 

 It is impossible to consider these in any other light, 

 than as beds of sandstone, originally deposited in 

 the places they now occupy, as their direction is 

 always conformable with the surrounding rock. 

 In one place, I observed a partial bed of sand - 

 stone, in the form of fiat anastomosing branches ; 

 the intermediate spaces being filled with clay- 

 stone-porpliyry. In another place, the sand- 

 stone v/as imbedded in felspar-porphyry, into 

 which it passed by an insensible boundary, and 

 included portions of the felspar, whose surfaces 

 were intimately incorporated with the sand- 

 stone. All these rocks, which I have mentioned 

 as included in the amygdaloid, are seen to tra- 

 verse it in the form of contemporaneous veins. 

 Even the sandstone in one place formed a vein, 

 intimately united with the amygdaloid at the 

 sides, and having the direction of the slaty frac- 

 ture parallel with the surface of the bed ^ in this 



