216 PROF. BOSWELL OK THE CBETACEOTTS AND [vol. lxxix, 



colourless, glassy grains, 02 to - 4 mm. in diameter : that is, 

 considerably larger in size than the grains of most other minerals. 



Staurolite is by no means plentiful. The grains are not 

 ragged at the edges, and do not exhibit the prismatic and pina- 

 coidal cleavage. 



Pleochroic andalusite is rare at several localities, but on the 

 whole is moderately abundant. Grains full of stony inclusions 

 (? broken chiastolite) have also been found. 



Kyanite is either rare or absent. The records of epidote, 

 common hornblende, and chlorite are from single grains. 



Garnet is again very rare, a solitary grain having been noted. 



Anatase is not uncommon in certain localities. The variety 

 •observed was indigo-blue, and crystallized in flat tabular crystals 

 with a small development of the pyramid faces. 



Fig. 4. — Hexagonal grains of corundum in Eocene deposits. 

 X 60 diameters. 



[4 a is from Great Haldon, western side ; 4 b from Little Haldon, 

 south-eastern end.] 



Corundum is persistent in its occurrence as hexagonal grains, 

 determined probably by the basal parting (see fig. 4). The 

 ' royal-blue ' colour is patchy, the refractive index high, and the 

 grains give a negative uniaxial figure. 



Prom the foregoing notes it is clear that there are many points 

 of similarity between the residues of the deposits from Buckland 

 Brewer and the Haldons, but that the Marazion residue is richer 

 and of rather different type. We may, moreover, rule out the 

 Marazion material, on general grounds (p. 213), as not likely to be 



