Microphotographs of rock types in the Central Series. (a) and (b) Gabbro veins. Olivine and clinopyroxene crystals are situated in ‘pathways’ between larger pyroxenes. Tabular plagioclase crystals are twinned and randomly oriented (CPL and PPL, respectively). (c) and (d) Feldspathic peridotite (breccia matrix) vein intruded into peridotite. The vein contacts are indicated by yellow dashed lines (CPL and PPL, respectively). The veins connect to more voluminous harrisite ‘pools’ and olivine crystal morphology (c.f. O’Driscoll et al., 2007a), suggest an intricate link between feldspathic peridotite and the harrisite in the Central Series. Note the difference in olivine crystal morphology between panels (c)–(f) and (g)–(j). (e) and (f) Anhedral to subhedral olivine with embayed crystal borders in feldspathic peridotite dyke. Plagioclase crystals comprise the interstices in-between the olivine grains (CPL and PPL, respectively). (g) and (h) Poikilo-macro-spherulitic feldspar texture in ‘pebbly’ peridotite. Subhedral to euhedral olivine is poikilitically enclosed in plagioclase and clinopyroxene (CPL and PPL, respectively). The olivines (high relief) are unsorted (from 0·1 to 10 mm size) and have different shapes with some crystals showing eroded edges. The olivines also occur in clots.