124 



I. II. III. IV. V. 



Si0 2 38-50 ... 38-60 ... 37-15 ... 39-50 ... 38-86 



Insol. in 

 HC1 



100-58 100-00 100-00 ] 00-00 100-30 



Sp. Gr. 2-587 .. 2-65 ... 2-56 ... 2-545 ... 



I. Black serpentine near Cadgwith containing porphyritic crystals of bastite. 



The crystals lose 9 p.c. on ignition. This agrees with the optical determina- 

 tion, and proves them to bebastite. Analysis by Mr. HCDDLESTOX (Q.J.G.S., 

 Vol. XXXIII., 1877, p. 925). 



II. Greyish-green granular serpentine. Porthalla. Analysis by Mr. COLLINS 



(Q.J.G.S., Vol. XL., 1884, p. 467). 



III. Dark oil-green serpentine. Porthalla-. 



IV. Keddish-brown granular serpentine. 1'orthalla. Analyses II., III. and IV. 



are all by Mr. COLLINS, and quoted from the same paper. The SiO., includes 

 also the insoluble residue. 



VI. Ornamental serpentine from the Lizard. Dark groundmass blotched with red. 

 The rock contained also traces of MnO. 2-06 of the water was lost in the 

 water-bath. Analysis of J. A. PHILLIPS. Phil. Mag., vol. XLI., 1871, p. 101. 



At Clicker Tor, near the Menheniot Railway Station, and about three 

 miles south-east of Liskeard, is another small patch coloured as serpentine 

 upon the geological map. The rock has been investigated both by Mr. 

 PHILLIPS (1) and Mr. ALT/PORT.*-' It was well exposed during the construc- 

 tion of the Cornish Railway, and is, indeed, still quarried close to the Station 

 at Menheniot. At the time of Mr. PHILLIPS'S visit it exhibited a schistose 

 structure, and did not appear to be sharply separated from the surrounding 

 killas. These facts seem to show that here, as at Nare Head, the serpentinous 

 rock has been affected by earth-movements. When Mr. ALT-PORT examined the 

 rock its relations to the surrounding sediments appear to have been better 

 exposed, and he describes it as an instrusive mass. Speaking of the microscopic 

 structure of the rock (See plate II. fig. 2), Mr. ALLPORT says : " A thin slice 



(1) Philosophical Magazine. Vol. XLI., p. 100. 



(2) Q J.G.S. Vol. XXXII., 1876, p. 422. 



