244 



GREENSTONE. 



Upper 

 Galxeey. 



Wall-cases 

 6 and 7. 



161. 



-Large-grained porphyritic greenstone, formino- 

 part of a line of trappean rock to Bray Hill in Padstow 

 Harbour, where it is clearly seen to have been intruded 

 among the slates. 



Employed for building and for roads j the more compact 



varieties are excellent for the purpose.— St. Minver, Cornwall. 



1 62.— Pobphtritic greenstone, forming part of a long 



line of trappean rocks extending to and beyond St. Clether 

 and which are for the most part schistose in that direction 

 and occasionally vescicular. — Davidstow, Cornwall. 



163. — Pobphteitic greenstone, containing crystals of 

 felspar and kernels of green earth in a decomposing horn- 

 blendic base. — Carneddau, Builth, Breconshire. 



16 ■*• — Porpiiryritic greenstone, containing a vein of 

 hornblende. — Boswednan Cliff, Zennor, Cornwall. 



165. 



Porphyritic greenstone, composed of crystals of 



felspar : 

 geirwen, Anglesea. 



Part of a dyke. — Breinion- 



166. — Fine-gbained greenstone, composed of nearly 



f felspc 



Ihe specimen 



shows the natural joints, the surfaces of which have wea- 

 thered of a brownish colour.— Broom Close Bay, Veryan, 

 Cornwall. 







167— Porphyritic greenstone, composed of crystals of 

 felspar, a small quantity of quartz, and a few minute specks 

 of iron pyrites in a base of hornblende.— Grange Hill, near 

 Chair of Kildare, County Kildare, Ireland. 



Porphyritic greenstone, composed of crystals of 



Beyond Goodrevy Cove, St. 



168. 



felspar i 



Keverne, Cornwall. 



169. 



Eia 



fi 



r : "Porfido VercT- 

 Composed of a few 



greenstone. —Llanfechell Anglesea. 



lln T>^^ 



170. 



ORpiiyritic greenstone, composed of crystals of 

 felspar in a base of hornblende. — Tan-y-graig, U 



miles N.N.E. of Pwllheli, Caernarvonshire. 



1' 



V 



,, p 







A 



: 



e 



ft 



>■ 







174- 



c< 



a. 



$ rod 

 thero 



qua 



: 



j mi 



jiniguK 



L 



aooa 



mt 



!fl enif 



ar E 



m 





na 

 in. 



it It, 



i II 



( 



*«i 



