S. Melmore — Metamorpliisiin at CarrocJc Fell. 267 



perhaps that the biotite is everywhere completely converted into 

 magnetite. 



The pectolite gave on analysis :— 



99-46 



Specific gravity . . 2-79 



Small masses of calcite about 1 cm. across and containing traces 

 of strontium are sometimes found with the pectolite.^ 



A section cut from this pectolite specimen showed under the micro- 

 scope a thin layer of white mica between the pectolite and 

 surrounding rock, while a narrow string of this mica ran parallel 

 to the main vein of pectolite and at some distance from it. Flakes 

 of sericite can be seen in the felspars adjacent to the vein. Analysis 

 of the rock itself showed only a trace of carbon dioxide, with O'OTi per 

 cent sulphur. 



The greater part of the lighter-coloured gabbro, which is about 

 2 feet in thickness at the margin of the intrusion, consists of 

 plagioclase in a more advanced state of decay ; the whole 

 of the crystal is reduced to a translucent mass, through which the 

 core of previously decomposed matter can still be seen in some 

 instances. 



Almost colourless serpentine occurs in places, associated with 

 magnetite in large, approximately square sections, and in small 

 granular inclusions, while separate areas of fibrous chlorite are also 

 present. 



Occasionally small hook-shaped areas of isotropic material with 

 felspar inclusions can be detected between the felspar crystals. 

 There are also a few well-defined crystals, giving a biaxial interference 

 figure and possessing very weak double reflection, that probably 

 represent a member of the zeolite group. The quartz present in 

 the rock is full of liquid inclusions, the length of the larger of these 

 being about 0'006 mm. and the diameter of the bubble 0'0015 mm. 



This rock, which represents a maximum degree of metamorphism 

 observed, loses 2" 12 per cent of its weight on ignition. For the 

 normal quartz-gabbro Dr. Harker gives the loss on ignition as 

 1*50 per cent.' 



From the above account it may be concluded that hydrothermal 

 metamorphism has taken place at the margin of the gabbro intrusion, 

 resulting in the serpentization of the original pyroxene, accompanied 



^ The material taken for analysis was free from calcite. 

 2 Quart. Journ. Geo!, Soc, vol. 1, 1894, p. 323. 



