200 SERPENTINE. 



at the Lizard in Cornwall, in Anglesea, and at Port- 

 soy. At this latter spot, the intermixture of the dif- 

 ferent rocks is somewhat intricate; gneiss, chlorite 

 schist, limestone, and serpentine, all occurring in an 

 irregularly alternating order. In Aberdeen shire, simi- 

 larly, it occurs in company with almost all the primary 

 class except quartz rock; with which I have never 

 yet seen it associated. If, lastly, it hears a peculiarly 

 intimate relation to talcose schist and diallage rock, 

 that has heen noted in the descriptions of these. 



Thus far, the history of Serpentine has also justified 

 its rank in the primary class; nor need it he deprived 

 of its place there hecause of the circumstances ahout 

 to be described. In Sky, where trap veins penetrate 

 white crystalline limestone, the parts in contact with 

 the calcareous rock consist of serpentine, to the depth 

 of an inch or more. There is also a gradation between 

 the serpentine and the trap, which is a black clay- 

 stone; so that a perfect transition takes place between 

 the two. Similar appearances, less remarkable, occur 

 in the same island, where trap veins intersect a series 

 of calcareous sandstones, being further displayed, but 

 on a more extensive scale, and in a more distinct 

 manner, at Clunie in Perthshire, as I originally 

 showed. Here, where a basaltic vein traverses lime- 

 stone, the sides of the former consist of serpentine 

 to the depth of four or five inches, passing into the 

 basalt by an imperceptible and perfect gradation, 

 while the rifts are also filled with varieties of stea- 

 tite and asbestos. In these instances, moreover, the 

 limestone near the contact is intermixed for a similar 

 space with steatite ; so that there is often an almost un- 

 interrupted gradation, through steatite and serpentine, 

 between the two highly discordant substances, basalt 

 and limestone. This connexion between basalt and 



