316 ME. J. J. H. TEALL 02^ EOCK-SPECIMEls^S COLLECTED 



(3) Dark-coloured, fine-grained granulite or grannlitic gneiss. 



The last-mentioned rock is largely composed of a fine-grained 

 micro-crystalline mosaic of quartz and felspar, in which needles of 

 actinolite lie imbedded. Iron-ores are fairly abundant. Certain 

 bands are rich in turbid felspar-pseudomorphs and larger grains 

 of hornblende, so that the rock is not a typical granulite. 



Mulvin. — Dark-coloured, fine-grained granulite or granulitic 

 gneiss similar to the rock just described from the Stags. 



Ils^NEE GeOUP. 



Enoch UocTc. — ^Coarse hornblendic schist and gneiss (without 

 quartz), quite distinct from the tonalite-gneiss and having close 

 affinities with the hornblende-schist of the mainland. 



Pen Ervan. — (1) A somewhat fine-grained, evenly foliated tonalite- 

 gneiss. 



(2) Brown micaceous rock, similar to the transition rocks of 

 Labham Eeefs. 



Labliam Reefs. — (1) Light-coloured or brownish granulite or 

 granulitic gneiss. 



(2) Brown micaceous schistose rocks intermediate in character 

 between the granulitic rocks of the islands and the mica-schists of 

 the mainland. 



Labham Rock. — (1) A finely crystalline pinkish granulitic rock 

 without well-marked foliation. Under the microscope this rock is 

 seen to consist principally of quartz and turbid felspar. It contains 

 also a very little hornblende and a few grains of epidote. The 

 granulitic structure is well developed in places. A narrow vein 

 containing much epidote traverses the slide. 



(2) A rock similar to the above, but somewhat richer in the darker 

 constituents. Under the microscope turbid felspars (original ?) are 

 seen to lie in a granulitic aggregate of colourless quartz and felspar 

 (secondary?). Long needles of actinolite lie in the granulitic 

 material. This rock possesses, in a certain sense, the " mortar- 

 structure " of Tornebohm. It is, however, the " mortar " and not 

 the " stones " that constitutes the greater portion of the mass. 



(3) A banded and corrugated granulite or granulitic gneiss. 

 Men Par. — Tonalite-gneiss of the Men-Hyr type. 



The Shag Rocks. — Bocks similar to those from Labham. 



Wiltshire. — (1) Light-coloured, banded granulite, showing a finer 

 foliation than that of Labham, but belonging to the same type. 



(2) Granulite of the same colour, but without conspicuous banding. 

 Under the microscope this rock is seen to consist principally of 

 quartz and felspar, the latter mostly unstriated. Perro-magnesian 

 constituents are sparingly represented by a little green mica. The 

 micro-structure of the rock is thoroughly granulitic. 



The Quadrant. — ^(1) GranuHte of the Wiltshire type. One spe- 

 cimen contains garnets and a little hornblende. 



(2) Porphyritic greenstone (epidiorite). 



Sanspareil. — ^^(1) Granulite without well-marked banding, com- 



