MODE I. SIDERITE. |5 



without any appearance of a regular form. It is 

 likewise more or less fusible under the blow-pipe. 



" The felspar also varies by its white colour 

 more or less pure, and inclining sometimes to 

 a green or rosy hue ; and by its form which, at 

 one time, presents pretty regular rhomboidal la- 

 minae, at others a crystallisation quite confused 

 in small granular masses, like statuary marble. 

 There is sometimes seen in the leaves, as in the 

 knots, a mixture of a little quartz. The felspar 

 which enters into the composition of this schistus 

 is commonly of that kind which I have termed 

 feldspath sec, or dry felspar ; I have however seen 

 but only one piece, of which the felspar was gras, 

 or unctuous." 1586, 



He also mentions 



2227. A green rock, which he would formerly 

 have called roche de corne, but must now refer to 

 the hornblende slate of Werner : and, 



1971. A gneiss, composed of laminar siderite 

 and felspar, on the ascent of Mont Blanc. 



2271. A slate of fine scales of mica and horn- 

 blende, sometimes in level plates, sometimes un- 

 dulated. It is of an olive-green colour, acts faintly 

 upon the magnet, and makes a hasty effervescence 

 with acids; a proof that it contains some cal- 

 careous particles. 



2131. Near Macugnaga, brilliant hornblende 



