278 
I^liekdan P. Thomson. 
(b) “(’oiitnct’’ Quartz Veins. These occur at several places on the 
gTanit(‘-»'iieiss-Car(lui> Series contact. One is well develojjed south of the 
Brickworks Quarry aiul it closely resembles the noi'th-soutli type of blow 
of Ai'inadale. It contains sericite bands and the quartz shows cataclastic 
structures. 
(e) Vein ([iiartz in the baritic sandstone. “The (luartz-barite veiiP^' 
(ClarkOj 19.30, ]). KiO) at Cardiip is sandstone which is veined and i)artly 
replaced by later quartz and barite. 
In lliin section the Aadnlets are setm to consist of clear quartz forming 
a inozaic of slightly straiiUHl crystals. 
(d) Narrow \(‘ins of vitreons quartz, up to one inch wide, occur in the 
black slate of the Brickworks QuariA'. The ([uartz is limpid and shows 
undulose extimdion. 
Origin of the quartz veins in the Cardup Series : — In the light of 
other eviflence, indicating that the Cardup Series is ]>ost granite in age, it 
is sugge.st(‘d that these veins are the residt ot' a period of vein formation 
that followtal tlu' intrusion of the epidiorite. The veins are possibly the' 
result, of difterentiat ion of the basii- magma. 
Coulson (1983, ]). 114) suggests sudi an onlgin for the quartz reefs 
associat(Ml with f'ertain Indian barite dejiosits. Although the age relation- 
ship betwetm the epidiorite and (fuartz veins in the Cardup Series has not. 
been determined \u the Wongong-Cardup area, post-e])idiorite quartz veins, 
are known to oc('ur at localitic's iu*ar the arc^a. 
Prider (1911, p. 42) ineiitions tliat at Armadale, in the tunnel west of 
the slate quarry, vein-lik(‘ bodies of ((iiartz that show jmouounced cataclastic 
structures occur in uralitise<l {|uarlz dolerite. 
Bsson (192(1, ]). 7) states that (jiiarlz r('efs of the silver lead deposits- 
at Mundijong occur in the epidiorites whi{di intrude the slate of the Cardup 
Series. 
4. Origin of the harUe . — The minerals associated Avith the barite in the' 
sandstone are quartz, pyrite, chalcopyrite, calcite, and purple fluorite. These 
minerals, except i>ossil)Iy the calcite, apjiear to be the result of one period 
of mineralisation. 
Because of tlu* irregular distribution and the abs(*nce of banded veins,, 
the paragenesis cannot be worked out. Nevertheless, sucli an association of 
minerals indicates a hydrothermal origin for the barite (Laurence, 1939, 
l>p. 190-290). 
Prider (1941) suggested that the silv<‘r-lead bearing veins of Mundijong 
and the barite and (luorite are l)oth r(*la(('d to the albite epidiorite magma. 
Coulson (1933, p. 115) considers that the barite of certain Indian deposits 
are derived from a somewhat simitar basic magma. 
AVhatever their source, the hot bai’ytic solutions appear to have ascended 
into the jAorous basal sandy beds of the Cardup Series iii many ])laces. 
Solutions containing barium ions have also migrated along the fracture planes- 
of the slates, where barite has l)een deposited (]">. 275). 
E. Later Bocks. 
1. Lateri{e.~V\\Q. distribution of this rock has been desciibed (p. 270). 
The high level laterite is the common pisolitic variety, and it does not 
appear to vary mai'kedly in composition, whether developed over epidiorite 
dykes or granite gneiss. 
