1823.] Analyses of Books. 45 



Article XII. 



Analyses of Books. 



Transactions \ of the Royal Geohmcal Society of Cornwall, 

 To/.//.l§22. ■^ 



(Concluded from voL v. p. 300.) 



The third order of veins described by Mr. Carne is that of 

 true veins, which consist of the following classes, enumerated in 

 the order of their relative ages, as determined by the principle 

 of intersection : 



1 . The oldest tin lodes ; 2. The more recent tin lodes ; 

 3. The oldest east and west copper lodes ; 4. The contra copper 

 iodes ; 5. Cross courses ; 6. The more recent copper lodes ; 

 7. The cross flukans; 8. The slides. 



" In describing the contemporaneous veins," he observes, 

 ^' some were mentioned as occurring in the veinstones of other 

 veins. There are also metallic veins which may be denominated 

 veins within veins.'' These comprise black and grey silver ore, 

 with native silver, in the copper lode of Huel Ann ; wood-like 

 and common tinstone in quartz and tinstone, the latter crossing 

 the veinstones of the lodes ; various ores of copper, in the quartz 

 veinstones of Huel Carpenter, Huel Neptune, Huel Damsel, &c. ; 

 woodlike oxide of iron, in brown ironstone, at Botallack and 

 Boscagel Downs ; fibrous oxide of iron, in quartz, and veins of 

 carbonate of iron at Huel Jubilee ; and minute veins of native 

 bismuth, in coarse red jasper, at Botallack. 



Some remarks on the geological constitution of that part of 

 Cornwall in which most of the veins described are found, and on 

 the number and variety of the veins themselves, terminate the 

 paper. After saying, " the claim of the granite which forms the 

 chain extending from the Land's End to Brown-willy, has rarely, 

 if ever, been seriously disputed;'' and adverting to the supposi- 

 tion that St. MichaePs Mount is transition granite, Mr. Carne 

 continues : 



^'The claims of the clayslate, however, have of late been dis- 

 puted, and it has been called transition slate, and greywacke 

 slate, by geologists whose authority certainly carries considera- 

 ble weight : but by what rules are we to distinguish primitive 

 from transition slate ? In its structure, the clayslate of Cornwall 

 appears, in general, perfectly homogeneous. It contains no 

 impressions of any kind. Some of the oldest metals have been 

 found in it, viz. oxide of tin, wolfram, and mispickel; these have 

 been discovered m the slate ; and they have also been found, 

 together with sulphuret of tin, native bismuth, and oxide of 

 liruniuni, in the veins which intersect it. Some of the oldest 



