Aggregate composed of amphibolite, gneiss and granite submitted from secondary mineral content (AS 1141.26), as this isn’t a mafic igneous rock the standard has to be modified. Meta-greywacke submitted for petrographic analysis for use as concrete aggregate, road base, rail ballast, marine armour rock and asphaltic/sealing aggregate and petrographic assessment of potential for alkali-silica reactivity. Harden Concrete Core submitted for petrographic analysis, image shows and example of Alkali-Silica Reaction (ASR). The Air bubble is filled with ASR gel. Micro-graph of early Ettringite Reaction a benign form filling in a air-bubble within a concrete core. Micro-graph of Delayed Ettringite Reaction a deleterious form causing the cracking observed within a concrete core.