WHITE : OATIAND COMPLEX OF IGNEOUS ROCKS. 127 
Biotite is sparingly present to absent in its pale green variety. 
One less-altered individual of the other variety appears with 
rather strong pleochroism in two shades of brown, but it is also 
( turbid in places like the more oxidised crystals. The latter are 
fairl}^ abundant with pleochroism of brown and olive-brown. In 
addition to the basal cleavage of a mica there is occasionally a 
poor cleavage not unlike the prismatic cleavage of an amphibole. 
The following (Figs. 9 to 12) wiU give an idea of its outline 
and that of the associated iron ores : — 
Fig- 11 Fig. 12. 
