part 2] TERTIARY OUTLIERS OF THE WEST OF ENGLAND. 209 



always biaxial, and is sometimes full of inclusions. Hexagonal 

 flakes occasionally occur. 



Grlauconite occurs as deep-green irregular or mammillated 

 grains, or as casts of foraminifera. Very fine examples, 05 to 

 0"6 mm. in diameter, are seen in samples of sand from the 

 northern end of the Great Haldon Hills. 



Zircon is present in all samples, and occurs both in rounded 

 grains, and as crystals with well-developed faces. Brownish 

 grains resembling zircon in form may be xenotime. 



Rutile is not so abundant, but the foxy-red variety is often 

 present. The yellow variety is less plentiful. 



Fig. 1. — Graphical representation of typical mechanical analyses 

 of the Greensand deposits. 



100% 



90. 



80 



[ 70 J 



■jj 40 



^ on 



3 .'0 . 



u 

 A 



20 

 10 



ltt ;e Haldon. N. .side. 



40 20 1-0 0-5 0-25 001. 005 0-01 

 >- Grade- Sizes (diameter in millimetres) 



Yellow tabular anatase is occasionally seen, and the indigo-blue 

 variety of the mineral occurs as flat tablets on the basal plane, which 

 is bevelled and truncated by the first- and second- order pyramids. 

 Pyramidal grains also occur. 



Andalusite, in clear glassy grains, sometimes prismatic and 

 showing blood-red or pink pleochroism, is frequently present. 

 Grains dusky with inclusions have been noted only occasionally. 



Kyanite, which occurs in the well-known tabular grains with 

 cross-cleavage, is on the whole rather uncommon, but is abundant 

 at certain horizons. It is never so plentiful as in the Pliocene 

 deposits of St. Erth. 



