SCALPA. GEOLOGY. 1()9 



between the gneiss and the proper serpentine, is a serpen- 

 tine so full of hornblende in large crystals as to be dis- 

 tinguishable with difficulty from a hornblende rock. 

 Some of the varieties have a schistose aspect and fissile 

 structure, their colours being likewise disposed in a 

 laminar manner, so as to present a dark greenish basis, 

 striped, and in some directions speckled with a paler 

 tone of the same colour. These generally lie near the 

 gneiss, the interior gradually assuming a more massive 

 form, and displaying at length a fracture from which all 

 appearance of foliated tendency has vanished. Talc slate 

 is also occasionally found at the limit of the gneiss, 

 mixed more or less with quartz of a very greasy aspect. 

 In the interior of this bed, of which the thickest part 

 may perhaps be estimated at 100 yards, a body of pot- 

 stone is found, the harder serpentine passing into it by 

 gentle degrees. The fine edge of its fracture is some- 

 what translucent, like wax, and it is of a dark green 

 colour. The serpentine contains,, as is not uncommon, 

 veins of dark green and of pure white steatite, sometimes 

 fibrous, together with splendent veins of greenish asbestos. 

 It offers no specimens of an ornamental nature. There 

 are some peculiarities worthy of notice in the gneiss 

 which accompanies it. In some parts this is almost a 

 mere mass of felspar with a splintery and granular frac- 

 ture, and mottled with red and white ; the laminar dispo- 

 sition being marked by these alternations of colour. 

 Sometimes it is interlaminated with clay slate, and more 

 rarely with talc, forming a talcaceous gneiss, a rock 

 which I have only observed in this place and which 

 serves to mark the connexion between the serpentine 

 and its boundary. A more remarkable phenomenon is 

 offered in the passage of the granite veins. They traverse 

 the serpentine as well as the gneiss, in the former part of 

 their course assuming a peculiar character, consisting of the 

 usual mixture of quartz and felspar with talc superadded ; a 

 proof that in this case at least the vein is influenced by the 



