MINERALOGY OF THE LIZAED DISTRICT. 183 



twinning is visible to identify it. In the dyke is fresh augite and 

 enstatite, and again the whole is fractured, and the fissure filled 

 with beautiful marmolite. 



Slide 8. — From Coverack. — Part of a kernel of decomposed gabbro, consisting 

 of felspar, hornblende, diallage, sphene, and magnetic iron. 



Slide 9. — From Coverack, consisting of old serpentine with new-formed dyke 

 of augite and enstatite, very brilliant under polarized light; also, 

 some veins of marmolite, passing through enstatite. 



Slide 10. — From Coverack. — (plate A fig. 2) — Kernel of altered gabbro, with 

 felspar much changed, augite far advanced into hornblende, and 

 some good crystals of sphene, and much magnetic iron. 



Slide 11. — From a small dyke at Coverack. — Consisting principally of labra- 

 dorite, sphene, and some small grains of olivine. 



Slide 12. — From Coverack. — (plate C fig. 10) — Olivine and enstatite, each 

 changing into serpentine; the difference in the two serpentines is 

 most interesting, the olivine serpentine contains more iron, and 

 is much darker than the enstatite serpentine ; of frequent 

 occurrence. 



Slide 13. — From Manacle point. — Containing augite and felspar,much altered 

 but not broken. 



Slide 14.— From a quarry by the road-side, at the head of Porthoustock 

 creek. — (plate B fig. 8) — Contains some clear crystals of felspar 

 and radiated hornblende, similar to those surrounding kernels 

 of olivine further south ; where it comes in contact with felspar, 

 the latter mineral is deformed or wasted ; actinolite too, is 

 present, and some well-preserved crystals of magnetite. 



Slide 15. — From Porthallow. — A serpentine rock after olivine and enstatite 

 changed into talc, bastite, and much iron ; it also contains some 

 good veins of marmolite. 



Slide 16. — From Porthallow. — A banded serpentine, with kernels of olivine 

 and enstatite yet unchanged. 



Slide 17- — From Porthallow. — Containing fragments of opaque felspar, and 

 anthophyllite. 



Slide 18. — From Porthallow. — A banded serpentine, apparently after olivine 

 and enstatite. 



Slide 19. — From Porthallow. — (plate C fig. 9) — A serpentine containing a 

 crystal of enstatite only partly changed into serpentine ; where 

 the change has taken place, it appears as if it were a solution, 

 but there is no evidence that the solution has passed along a 

 fault or fissure ; the fibres of the enstatite show no evidence of 

 curvature or breakage. 



