70 DOMAIN IX. ANOMALOUS. 



ble. Among them are the variolites of Drac; 

 and another variolite, of laminar siderite, of a 

 dull black inclining to green ; spangled with 

 crystals of felspar, sometimes rhomboidal, some- 

 times circular, with green dots of hornblende 

 towards the centre. Saussure observes, that it 

 somewhat approaches to the ocular granitel of 

 Corsica, the crystallisation being only more 

 confused. 



The following detached observations of this 

 skilful Petralogist, may throw additional light on 

 this subject. He supposes, 159* that layers 

 in zigzag probably arise from crystallisation, as 

 they do in alabasters : and 2227, he mentions 

 layers in zigzag, in a granular lime-stone, mixed 

 with mica, included between other veins which 

 are parallel. Such layers, he adds, are not only 

 found in crystallised rock, but in slate, which 

 presents no appearance of crystallisation. 



The ocular appearance is also found in other 

 rocks, and Faujas has formed a series of this 

 kind. Saussure indicates, 16 1, mica slates 

 often containing nodules of quartz, which, when 

 cut across, appear like eyes. Sometimes they 

 are as small as grains of millet; and others are 

 two inches in diameter. 



An ocular serpentine is also found in Corsica. 



