Thursday, March 7, 2013

Exploring Gemstone Beach

Scouts from the Riverton Scout Venture at Gemstone Beach

The Riverton scout Venture was held in early January.  There was a good turnout and despite one or two scares with the weather it turned out OK with the high winds and torrential rain by-passing Riverton.  I helped sort out the gear and took fieldtrips to Gemstone Beach.  We weren’t lucky with the tides but still had a great couple of hours each time fossicking.  The seas were high and surging up the gravel slopes and we all got wet feet.  It’s a bit risky I guess but the Venturer motto is ‘Look Wide’ so if they are swept away it’s their own fault.  They must have grown up with the scout motto ‘Be Prepared’ as well.  They were reasonably prepared for the Venture but most of the Venturers are from Australia and they can’t conceive of how cold and wet it can be in Southland in the middle of summer.  There were some quick trips to buy winter clothes when the temperature dropped.  This is a problem with overseas tour groups as well.  They are told they are coming from a northern hemisphere winter into a tropical land, only to find that there can be snow and cold winds.

Anyway the only casualty of the beach foray was a small dog – a ‘rat-on-a-string’ sort of critter which was swept off its feet and tumbled out into the surf.  Fortunately it was tethered and it was easily wound back in again.  It shook the foam off and carried on sniffing.  We were reasonably successful with the stones and everyone ended up with at least one garnet.  These are translucent green, amber or white and are noticeably glossier and heavier than the other stones.  One girl picked up a fist-sized pale green garnet.  Once, I would have been jealous, but advancing age changes your perspective on things, and I found myself being as excited for her with her treasure as she was.  The prize mineral from the beach is sapphire.  I’ve seen them in collections but we didn’t have any luck finding one.  Gemstone Beach ‘works’ because of the geography of the coast.  The heavier stones coming down the Waiau River plus the heavy sand – iron sand – with its speckles of gold and platinum, are concentrated by wave action along a relatively short distance.

 A selection of gemstones

 The beach also has lumps of shale which I flaked with a pocketknife and burned with a match.  “Smells like burning oil,” they said.  No wonder – it is burning oil.  When you bang two quartz pebbles together they spark although you can’t see that in daylight.  The bang also produces a smell like gunpowder.  I tell kids they can carry on reading their good book after lights-out by the illumination of quartz sparks.  ‘Once upon a time’ – spark – ‘there were three bears’ – spark – etc…   My best find was a rhodonite pebble.  It’s a striking pink tone with black squiggles.  It’s not particularly rare but it’s the first time I have picked up rhodonite.  The last mineral worth mentioning is coal.  There are lumps of it there, probably from a seam just offshore but possibly from a shipwreck.  I find myself compulsively collecting coal from the beach.  I think it is a primitive instinct that hasn’t been purged out completely.