WHITE : OATLAND COMPLEX OF IGNEOUS ROCKS. 
129 
malacolite about .5 mm. by .5 mm., with strong D. Refraction. 
Similar phenomena belong to another crystal measuring 2.4 mm. 
by 2.3 mm. A still larger crystal, 2.9 mm. by 2.5 mm., shows 
multiple twinning like the augites in the rock at Poor town, but 
more hornblende appears to have been originally included and 
more iron-ores have been liberated. Quartz has penetrated the 
crystal in several directions. 
A few general observations may here be made respecting 
this sub -angular basic xenolith. Near the margins of the frag- 
ment the minerals are arranged — like the whole of the xenolith 
found in the heart of the boss — as a confused aggregate of minute 
crystals crowded with amphibole, while the felspars of the sur- 
rounding granodiorite lie tangentially to the outline of the knob. 
The acid portion of the slidk shows an abnormal quantity of the 
darker oxidised biotite, and, to a less degree, of plagioclase. It 
appears as though the matrix of amphibole had been dissolved 
from the surface of the xenolith leaving the biotite and felspar 
and a little augite free in the solute. Near the included fragments 
the hornblende has recrystallised in good idiomorphic forms 
unlike its usual habit elsewhere in the boss. 
ORDER OF CRYSTALLISATION IN THE INTERMEDIATE TYPE. 
Similar considerations affect the determination of this as 
are noted in connection with the basic type. 
5. Compact hornblende. 
6. Fibrous hornblende. 
7. Quartz, when present. 
SUGGESTED AFFINITIES. 
The intermediate type may be described as an augite-horn- 
blende-biotite-diorite. Mineralogically it resembles the rock 
from Seathwaite How (Teall, Brit. Petr., p. 276). The calculated 
APPARENT ORDER. 
1. 
2. 
3. 
4. 
