"Upper 



Gallery. 



Wall-cases 

 6 and 7. 



238 



ELY AN DYKES. 



It forms a dyke which can be traced for 12 miles from 

 Huel Darlington, near Marazion, into the Carnbrea granite, 

 cutting into the latter on the west of Camborne Beacon 



) Map. 



Marazion 



(See "Report on Cornwall," p. 174 

 Mines, Cornwall. 



105a. — Porphyritic rock, composed of crystals of/e7- 

 spar and quartz, in a felspatho-quartzose base, from an 



el van dyke adjoining the copper and tin lodes. 

 33. — Marazion Mines. Cornwall. 



Map 



106. — Felspathic porphyry, composed of quartz and 

 crystals of felspar, some of which are weathered out in a 

 quartzo-felspathic base. It forms part of an elvan dyke. 

 Map 31. — Enys, Cornwall. 



107. — Part of an elvan dyke, a whitish rock com- 

 posed of a fine grained compound of quartz and felspar, a 

 continuation of the Penstruthal elvan, No. 91. Map 31. 



Newham Quarry, near Truro, Cornwall. 



107a. — A variety of the above elvan dyke. (See " Report 

 on Cornwall," p. 177.) 



108. — Felspathic porphyry, containing prismatic crys- 

 tals of schorl, and fragments of quartz in a quartzo-fel- 

 spathic base. Map 31. — Pentuan, St. Austell, Cornwall. 



109. — Felspathic porphyry, a variety of the Pentuan 

 elvan, composed of a base of felspar and quartz, with a 

 few small specks of silvery mica, and numerous large frag- 

 ments of the slate rocks which it traverses. From 

 outer portion of the dyke. (See " Report on Cornwall, 



the 



) Map 



Pentuan, St. Austell, Cornwall. 



109a. — Another variety of the Pentuan elvan, contain- 

 ing included fragments of slate. 



110. — Another variety of the Pentuan elvan, from the 

 outer portions of the dyke, containing an included fragment 

 of the adjoining rock. 



HI. — Felspathic porphyry, composed of crystals of 



flesh-coloured felspar, and translucent quartz, with spots of 



schorl, in a light-grey felspatho-quartzose base. 



33. 



Quarry 



Map 



/ 





\ 



$ 



m 



n 1 ' 





* 





s 



116/ 



i f> 



Corn* 1 

 Iff/ 



jrained 



118, 

 119, 



8( 



^ 



reins b 



in Con 



t\ pu 



Padsto^ 



