Vol. 59.] 



THE TINTAGEL AND DAVIDSTOW DISTKICT. 



415 



Tregrylls Farm, and form in some degree a connection between those 

 above described and others, more altered, to be mentioned later. 



Two specimens have been sliced ; the one contains some quantity 

 of impure sphene and idiomorphic crystals of epidote, 1 sufficiently 

 large to be visible to the unaided eye ; the other, while resembling 

 it in the possession of these two minerals, differs in containing a 



Pig. 1. — Crystals of epidote and sphene, with granules of ilmenite, 

 in a groundmass of chlorite and actinolite-jlaJces, X 40. South 

 of Tregrylls Farm, on the road to Lesnewth from Waterpit Down. 



'sai^E^l^^^^s^fe 



-*: 



greater proportion of dolomite and calcite and well-developed flakes 

 of biotite. The last-named mineral is brownish or yellowish-green 

 for vibrations parallel to the basal plane, and straw-coloured at 

 right angles to this, with a considerable degree of absorption. The 

 orientation of the flakes gives the rock a very schistose appearance. 

 Crystals of sphene are very numerous in the first slice (fig. 1) ; 



1 Enclosing allanite, to which reference is made en p. 416. 



