The latest phases of the intrusion form an elongate northwest-striking stock composed of pyroxene syenite and diabase that cut equigranular
syenite and biotite monzonite.
Texture varies from coarse-grained equigranular
to medium-grained porphyritic, the latter with phenocrysts of quartz and plagioclase up to 1 cm in length (Fig.
Gabbros are medium grained equigranular
with cataclastic microstructure near fault zones (milonites).
A total of seven holes drilled in the Winchester prospect suggest that gold mineralization is closely associated with light gray, equigranular
, fine- to medium-grained felsic intrusive sills and is not restricted to brecciated zones or veins.
The stock is quasi-concentrically zoned from a central fine-grained core, through a dominant megacrystic phase, to a peripheral equigranular
Some xenolith showed equigranular
texture with almost uniform small grains.
Three facies have been defined: 1, outermost coarse-grained seriate facies; 2, porphyritic medium to fine-grained facies; 3, innermost fine-grained equigranular
facies (phenocrysts rare to absent).
The hole comprises variably stockwork veined, medium to fine grained diorite and medium to coarse grained equigranular
granodiorite with overprinting phyllic alteration.
4f) is typically light pink to dark red, medium-grained and equigranular
, but in some places it is porphyritic with phenocrysts of plagioclase (~[An.
They are medium to fine grain-sized, with equigranular
and occasionally porphyritic hypidiomorphic textures (up to 10% of plagioclase phenocrysts).
The lintels, window frames, and cornices are a grey, medium-grained, equigranular
muscovite-biotite granite that appears to be a finer-grained variety of the tower base and doorway muscovite-biotite granites.
Mineralization consists of fracture-controlled veinlets and disseminated molybdenite-pyrite in quartz-Kspar alteration zones of equigranular
quartz monzonite and granodiorite.