C "2 3 



Third, sienite, which consists of the substance 

 called hornblende and feldspar. 



Fourth, serpentine, which is constituted by feld- 

 spar and a body named resplendent hornblende ; and 

 their separate crystals are often so small as to give 

 the stone a uniform appearance : this rock abounds 

 in veins of a substance called steatite, or soap rock. 



Fifth, porphyry, which constists of crystals of 

 feldspar, embedded in the same material, but usually 

 >f a different colour. 



Sixth, granular marble, which consists entirely 

 of crystals of carbonate of lime ; and which, when its 

 colour is white, and texture fine, is the substance used 

 by statuaries. 



Seventh, chlorite schist, which consists of chlo- 

 rite, a green or grey substance somewhat analogous 

 to mica and feldspar. 



Eight, quartzose rock, which is composed of 

 quartz in a granular form, sometimes united to small 

 quantities of the crystalline elements, which have 

 been mentioned as belonging to the other rocks. 



The secondary rocks are more numerous than 

 the primary ; but twelve varieties include all that are 

 usually found in these islands, 



First, grauivacke, which consists of fragments of 

 quartz, or chlorite schist, embedded in a cement, 

 principally composed of feldspar. 



Second, siliceous sandstone, which is composed of 

 fine quarts or sand, united by a siliceous cement. 



Third, limestone, consisting of carbonate of lime, 

 more compact in its texture than in the granular mar- 

 ble $ and often abounding in marine exuvia. 



