This sample displays minerals and textures which are interpreted in the following stages, from earliest to latest: 1. Crystallisation of micro-granitoid (micro-syenogranite) A fine-grained massive granitoid crystallised as an intrusion, forming minor phenocrysts (plagioclase = quartz) in abundant fine-grained micrographic groundmass (K-feldspar + quartz + plagioclase + minor biotite + opaques + trace others (zircon, apatite, ?allanite). Much of the K-feldspar and quartz formed as micrographic patches, and some quartz also formed discrete grains. Proportions of feldspars and quartz indicate it has a syenogranite composition. Presence of inferred magnetite and dark brown biotite pleochroism indicate the magma was moderately oxidised. 2. Alteration Circulation of a small volume of aqueous fluid produced an alteration assemblage of chlorite + hematite. The chlorite formed by selective alteration of biotite, and hematite formed pervasively but more densely in plagioclase grains.

In thin section, this sample displays a massive porphyritic fine-grained granitoid texture, modified by weak selective alteration effects. Phenocrysts occur in minor amounts: i) Plagioclase forms uncommon but large blocky prisms ~2-4 mm in size. ii) Quartz forms equant euhedral crystals of similar size. Groundmass is dominated by blocky but anhedral K-feldspar grains ~1-2 mm in size with intimately intergrown smaller quartz grains (micrographic texture). Presence of ‘tartan’ twinning confirms the K-feldspar is microcline. Quartz also forms equant subhedral grains ~0.4 mm in size, uniformly distributed through the rock. Plagioclase occurs as minor amount as subhedral small prisms ~0.4-0.8 mm in size. Biotite occurs in minor amount as small, randomly oriented flakes ~0.4 mm long, sparsely distributed through the rock. Pleochroism from straw yellow to dark brown suggests it has a moderately oxidised Fe-Mg biotite composition (see magnetite below). Some display partial to complete replacement by dull green chlorite and tiny rutile needles. Opaques occur in trace amount as small blocky crystals with cubic morphology. They likely are magnetite. Muscovite occurs as rare small but well-shaped flakes, at contacts of felsic grains. Zircon is observed as small squat prisms ~50 μm in size: some occur discretely in felsic grains, but one forms an inclusion within an opaque grain, and one forms an inclusion within an altered ?allanite crystal (prismatic crystal, completely replaced by very fine-grained dense green ?chlorite). Apatite occurs as rare small equant crystals (colourless, high relief, hexagonal basal section). Hematite occurs as tiny reddish specks and small clouds which pervade the rock. It is more densely concentrated in plagioclase grains, but also occurs in biotite flakes and along grain contacts.