The Contact Between the (Jkanitic I^ocks and the 
AT Akajadaee. 
CARuri’ 
Series' 
;i5 
which oecui's in well sliaixul prisins with il’iVLi'ular tcrniinnlioiis, towards 
which the biotite is idiol)lastic. The anipliibole has pleochroism, X brownish- 
g:reen, Y biajwnish f^veeti, Z ^T(‘en (slightly bliiisli) and absorption X ■' 
Y Z. The (‘xtinction Z A c is 18° and the oi>ticnI chai‘a('ter -ive. In 
several s])ecinu‘ns a. blLU‘-gre(‘n anii>hibole with X light y(’llow-gTeeji, Y 
olive green, Z liluish-giHaai, ahsorjition X < Y Z and Z A c •= 17°, 
is idioblastic lowai'ds the biotite. It (X'ciirs in elongated prisins, often in 
clusters with the long axes of individual pi’isnis snbparallt*]. 
Th(‘ e|»i(lole occurs in ])atches with an aggi’egate structure, made up of 
a mesh of tiny euhedral prisms, with which is associated some brownish- 
green biotite (in nuudi smaller Hakes than in the biotite-hoi-nlilende ai'cas). 
The epidote is practically colourless and brightly ixdarising pistachiie, 
although some tine granular zoisite a)>})ears to be pr(‘seut in the granular 
aggregates. These el>i<lotic areas appear to rejireseut a replacement of 
original calcic plagioclase. 
In one sp(‘cimen (1920!))* the original striu-ture of the ro<d< <'an be 
seen by an examiruilion <d' tin* slic(‘ under very low magiuticatiou — it is that 
of a coarse grained rock with plat(^s to 4 mm. diamelei* of blue-green 
amphihole (now partially rt'placed by biotite aggregates) and felspar (now 
comjihdely replm-ed liy epidote) and it lias undoubtedly originated fi*om a 
coarse grained basic igiU'Oiis rock. This is siipiiorted by the pr<*smic(* of 
skeletal plates of magnetite (lig. 3e) which apjiear to have been derivial from 
ilinenite plates. 
A. Hybridised granite gneiss — showing hasie clots consisting largely of greenish 
brown biotite, with magnetite and aj)atite. The granitic portion consists 
of an allotrioniorphic granular aggregate of niicroclinc (Yicr), tiirhid 
plagioclase (PI) and quartz (Q). 
B. Basic xenolith — courser variety of l)orid)lenrle4:)iotite-epi(lote lionifels show- 
ing occurrence of epidotic aggregates (Ep-Zo) in distiiu't areaf» 
(originally plagioclase crystals). Rliows also tlie decussate structured 
aggregates of biotite and liornhleudc (Hh), with magnetite and apatite 
(Aj)) euhedra, 
0. Basic xenolith — finer grained variety of hornl)lended)iotite-cpidote hornfols-, 
showing segregation of epidotic minerals in patches and large skeletal 
plate of magnetite (after ilmenite). 
* Catalogue number, Geology Dept., University of Western Australia. 
