476 



ME. II. H. READ 0>" THE 



["vol. lxxix, 



Within the area of xenolith-bearing contaminated rocks, the 

 blotched hornfels is replaced by a dense, compact, blue hornfels 

 which forms the dominant argillaceous xenolith. This rock is 

 usually quite massive, and but rarely shows a composition-banding - . 



Fig. 6. — JLenolitlis. 



C D 



A = Prisms of sillimanite and clots of spinel in a base of cordierite, with a few- 

 grains of jxlagioclase ; X 30. The original rock was andalusite- schist 

 of the Fyvie Series. (See p. 477.) 



B = Grains of spinel in cordierite; X 30. The original rock was the same as 

 in the case of A. An analysis of this rock is given in Table IV, p. 477. 



C = Garnet (Ga.), hypersthene (Hy.), biotite (Bi.), quartz (Qz.), and plagioclase 

 (PI.) ; X 30. The original rock was probably a grit of the Fyvie 

 Series. (See p. 477.) 



D = Garnet (Ga.), biotite (Bi.), spinel (solid black), and cordierite (colourless) ; 

 X 20. The original rock was a biotite-schist of the Ellon Series. (See 

 p. 478.) 



Certain of these hornfelses are deep blue in colour, and then break 

 with a glassy fracture ; they are almost pure cordierite. 



The minerals of these hornfelses are cordierite, spinel, sillimanite 

 and garnet, with plagioclase, hypersthene, quartz, biotite, and 



