Large (up to 6cm) circular orthoclase feldspars (pink) phenocrysts with growth rings of opaque minerals (hornblende?). Many of the feldspars have a plagioclase feldspar (green) rim. Some also display a growth ring of plagioclase. The rest of the granite consists of large (1cm) crystals of dark minerals and orthoclase.
Small growth rim of plagioclase suggests alternating temperature/chemistry of the melt?
This granite is located on the side of Bran Diamonds on Swanston Street, Melbourne. It's one of my favourite facias in the city. I always thought it was a lovely weathered example of orbituclar granite however when confirming it's origin I found this page and this page both of which suggest this is in fact Rapakivi Granite.
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