-. . 







\ 



■ 



fta 





.::. 



lb 



... 



: :z 



. 







s 



■ 



\* 







'■:■■ 



0b 







* 







GRANITIC DYKES. 



231 



crystals of schorl, radiating from different centres 

 crossing or pressing against each other. 



and 

 Rose- 



- , ° — w*. ±f±au oo. — itose- 



wlnfp n i6i.) ° 0rnWalL (See " Report on P4 



66.--SCHOBL vein, ftw^ ^,'fe, illustrative of the 

 mode of occurrence of such veins in Cornwall. Map 33 



wIi; , i? r l n ;i.! , :r" cEous ™ * ^w of 



felspa 

 serpentine. Map 



From a vein of granite cutting 

 •Flagstaff, Cadgwith, Cornwall. 



* ine-grained schorlaceous granite, comoospd 

 specks of sihmj mica . From a grM ' ite ve cu -™ 



69. 



M 



f^Jj^f^r 7™ : *? *!*»» b eon,- 



a lew small specks of *cAor/. 



/e&p 



felspa 



Poltreath, Lizard Town, Cornwall. 

 7U.— Granite vein, composed of a quart 

 base Wlth crjstals o? white felspar ^ a scattered equivocal 

 dark substance, probably schorl equivocal 



Map No. 30) extending from the main mass of granite east, 

 ward toward. St Mabvn. It has been employer ouilZg 

 and for roads ; the more compact parts of the dyke afford a 

 good ferial for the latter purpose.-Hellagon 7 , neafstl! 

 land Cornwall. (See "Report on Geology of Cornwall," 



p. 180.) 



71. 



felsp 



felslr T?^ dlSSGminated "7"* * %ht-coloured 

 No 8S* v f T mS / P° rtion of ^ granitic dyke noticed 



mlrf;, 7i° y l d f ° r r ° ads ' f0r Which * is an excellent 

 material, and for building Mnn sn t u 



St. Teath, Cornwall g ' P 3 °- Tre S reenwe11 ' ^ar 



Granitic dyke, the central portion of the dyke, and 



id ot quartz, felspar, and mica, with fi pnmtP ,™. 



72. 



tiio^^i '•'/'""' «*""• "«<-«, wnn sepai 



tais ot felspar and spots of decomposed iron pyrites. 



Upper 

 Gallery. 



Wall-cases 

 6 and 7. 



