482 T. W. E. DAVID, W. F. SMEETH, AND J. A. SCHOFIELD. 
The bulk analysis of the rock yielded the following results :— 
sid, ao =71-437% | 
Al,O, (P,0,). =11°03 
Fe,O, ie =. 18] 
FeO hi = 2°56 
MnO me “D2 
CaO = 407 
MgO see = 2°44 
Na,O "ee = 2°10 
K,O et oe 277 
H,O (on ignition) = 1-44 
100-17 
Phosphoric acid, chlorine and fluorine aré present in small 
quantities. 
The percentage of lime is notably large and a partial analysis 
of the biotite was made to see whether it contained any lime. 
This yielded the following :— 
SiO, =37-707 
Al,O, = 20-74 
Fe,0, =19-03 
MnO = 2:03 
MgO = 8-06 
The iron present as FeO was not determined. It was found to 
contain no lime. 
The above analysis shows that the mica, which has a decided 
bronze lustre, lies between biotite and lepidomelane in composition: 
It was also found to be uniaxial. The high percentage of Mn0 
is noteworthy and probably accounts for all the manganese found 
in the bulk analysis of the rock. (We may mention incidently 
that all the specimens of these Antarctic rocks which have so fa 
been submitted to analysis contain appreciable quantities of 
manganese). 
Lime being therefore excluded from the mica it became — 
sary to search for it elsewhere. No trace of twinning, whi 
FOR coe PERE Ce ae ees A a ae URS aa tr ae Teer 
