Oriental Bay Sand

Originally, Oriental Bay only had a narrow rocky beach consisting of pebbly sand derived from the Torlesse greywacke bedrock. There were a couple of attempts to build up the beach during the 1900's but the bulk of the sand which we see today was brought here between 2002 and 2003 when more then 22,000 tonnes of sand was delivered by barge. The sand originated from a quarry in granite bedrock near Separation Point in Nelson in the South Island. The granite crystallised within hot magma chambers deep underground on the margin of Gondwana, just before Zealandia (ancient New Zealand) separated from it. Slowly these rocks have been uplifted, exposed and weathered into sand.
Because the beach is such an active environment the sand is slowly lost into the harbour. So sand levels are monitored and are topped up when needed.

The sand itself is comprised of weathered granite which has been broken into smaller grains of minerals which can be identified. The darker grains are most likely biotite (mica) and hornblende, whereas the lighter grains are quartz and potassium feldspar. You should also be able to find Torlesse sandstone (greywacke) outcrops at either ends of the beach which is the original bedrock here.