38 PKOF. T. G. BONNET ON THE [Feb. 1896, 



and of small elongated prisms of colourless hornblende. It contains, 

 however, a number of small ' inclusions,' consisting almost wholly 

 of clustered ferrite, surrounded by a clear zone, not quite so broad 

 as they, of actinolite ; and two larger inclusions (?), much ferrite- 

 stained, recall the structure of a fluxion-breccia. This part of the 

 slice is separated from the grey baud by a rather sharply defined 

 border. The latter affords indications of a banded structure in the 

 presence of ill-defined lines of brown hornblende-grains (not 

 numerous), of felspar (?)-grains, and (chiefly) of a felted mass of 

 flaky or acicular actinolite, with which probably a colourless chlorite 

 is also associated. These specimens, with that from Pare Bean Cove 

 described above, lead me to the conclusion that their adjacent faces 

 indicate the junction-surface of the two rocks, but that here also 

 the outer part of the serpentine has been rendered impure by some 

 superficial melting of the hornblende-schist. 1 



The facts cited above, it may be worth while to repeat, seem to 

 indicate that the brownness of the hornblende 2 is one indication 

 of contact-metamorphism, while a more extreme result of the 

 latter is the production of a rather fibrous, somewhat minute 

 actinolitic hornblende and of sundry flaky minerals (representing 

 the aluminous constituents of the rock), probably light-coloured 

 chlorite or mica. 



Here I may refer to a section which has been mentioned more 

 than once in former papers, 3 namely, that exhibited in a low crag 

 at the foot of the main cliffs, north of Kynance Cove. On each 

 visit I have spent some time in studying it, without, however, 

 feeling much more certain as to its exact interpretation. As 

 described on the first occasion, serpentine occurs on either side, and 

 in the cliff above, the craglet in question, which exhibits, apparently 

 in vertical bands, " (2) a mass of grey, rather sandy, ' hornblende- 

 schist,' about 8 feet thick, with apparently many thin laminae of 

 red serpentine ; (3) red serpentine, rather fissile in structure, 

 2 j feet ; (4) a dark brownish-grey rock with crystals rather 

 resembling diallage, 2 feet; (5) red serpentine, 4 J feet, divided by 

 a thin [rather wedge-shaped] band of the schist, then bedded 

 schist like (2), with the apparent layers of serpentine, for about 

 6 feet." 4 



1 It may be well to remark that the serpentine of the Lizard is generally 

 very uniform in structure, and only departs from this rule (and that by no 

 means always) in the immediate neighbourhood of a junction with hornblende- 

 schist. 



2 I have more than once called attention to the fact that in hornblende a 

 brown colour often precedes the green ; the latter may indicate an early stage 

 in the process of hydration, affecting the ultra-microscopic grains of iron oxide 

 or some constituent to which the colour is due. 



3 Quart. Journ. G-eol. Soc. vol. xxxiii. (1877) pp. 888, 920; vol. xxxix. 

 (1883) p. 23. 



4 ' Rather more than 7 feet ' was my note in 1894 ; the measurements then 

 were a little more precise than on former occasions, but the differences are so 

 slight that I leave the passage as it stands. Between the last-named ' schist ' 

 and the serpentine (5) is a thin darkish dyke, which I had supposed to be part 

 of the schist, and there may be another in the latter. 



