(^LAKKE AND ^VlLLlA:^[S . — Gcolofjy of Dudiiuj Ttanye. 
16 y 
Most exposures show these segregations to be lenses parallel 
to tlio gucissie bamling, less commonly they occur as subangiilar 
lilocks strung out parallel to the gneissic banding. Tliey are cut 
by both biotite ]>ogmatite and quartz veins. 
Segregations identical with those of the Koleystone Area are 
exposed in Statham ’s Quarry just west of the S.W. corner of 
the Darlington Area, but have not been noted in the Darliiigtou 
Area. 
;b A(-id and idtra-arid inirusions .- — These occur as veins, dykes 
and irregular masses in the granite, into wliich they merge gradu- 
ally. The types re])resented are: — 
(a) Aplitic, biotite granite; 
(b) Aplite; 
(c) Biotite pegmatite; 
(d) iruscovite pegmatite; 
(e) Quai'tz veins. 
Aone except the aplitic Idotite granite shows any approach to 
gneissic structure. 
Field-relations and microscopic features indicate- that they 
sliould be placed in the above order in respect of age, the aplitic 
granite being the oldest. The position of the muscovite pegmatite 
is, however, uncertain. 
(a) The aplitic granite occurs in irregular masses as much 
as two chains wide. It is a medium even-grained rock composed 
of microclinc and oligoclase, Avith (piaitz and biotite. 
(b) Tlie exposures of aplite are generally smaller than those 
of the aplitic granite. The rock occurs in dykes and veins, and 
IS in many places associated with pegmatites. Petrologically i1 
differs from the aplitic granite in the very small development of 
biotite. 
(c) Numerous veins of biotite pegmatite, up to a foot or so 
ill wicltli, cut the gneissic bimcling of the granite mthout being 
distorted by it. They also cut the aplite and aplitic granite. The 
chief mineral constituent is mici'oeline in crystals up to six niches 
across. Oligoclase is subordinate to mierocline. As in the granite 
the mierocline is the less turbid of the tivo feldspars. ^ Biotite 
occurs ill “books” up to si.x inches across. The quartz is partly 
interstitial and partly intergrown wit!h feldspar. Also quartz 
veinlets, not optically continuous, traverse crack.s in the microchue 
crystals. 
