Panning on a New Zealand river

Many of the rivers on the West Coast of New Zealand's South Island contain gold. The gold has been deposited in the rivers from the rocks further up in the mountains. The gold is held in small vains and flakes in quartz. These quartz pebbles bash against each other in the river where the gold falls out. If the river if fast enough the water carries the gold, until at a bend or a widening, the water becomes slower, and then deposits in the mud.

Extracting the gold is possible with very simple equipment, but because it is widely dispersed it is hard work to collect a lot ! The way we do it makes uses of the fact that gold is very much more dense than other materials and so always tends to sink to the very bottom.

A pan is filled with mud and rocks which is then reduced by the process described below till only a very small fraction is left. This will be the very dense rocks and minerals such as gold and possibly other precious treasures ! I went off panning on several occasions and I could not find much gold near to Franz Joseph (the best gold carrying rivers were further away). However as the following pictures show there are other treasures that can be found.

Panning can seperate a few specs of gold from several kilo's of mud and rock. This is a seperation of about 1 part in a million - all with just a pan and lots of patience (and cold hands) !

Step 1: Find a wonderful New Zealand River

River near Franz Josef

Step 2: walk along the bank until you can find a place where you can dig up the mud easily.

on the river bank

Step 3: Look for a place where the water might be forced to slow, i.e. at a bend in the river or behind a large bolder.

collecting the mud

Step 4: place the mud into a pan and immerse it in the river. Take it out and using your hand swirl the water mud mix around so that the heavy gold will sink to the bottom of the pan. Take a few mins to do this. Then place the pan into the water and swish it around so that most of the meterial is washed out.

removing the light matter

Step 5: When 9/10 th's of the matter has gone. Remove the pan and add a little water and swish around. Then put the pan back into the water and with a carefull forward moving action push the pan into the water so that little waves of water take out the lighter material.

concentrating the heavy

Step 6: After about 5-10 mins most of the light material will have been removed and only a small amount of heavy 'stuff' will be left. Now be very carefull and repeat the process but every so often take the pan out and re-swirl the pan with about half a mugs worth of water.

heavy matter

Step 7: Eventually all the light matter will have gone and you will have a pan of interesting tiny dense rocks. In the example in the pictures I didnt find any gold but almost everything left in the pan after about 10 mins paning were tiny red garnets - a wonderful moment !

pan full of garnets

Step 8: Using a pair of tweezers carefully remove the garnets or the gold flakes by using a small amount of water to wash the precious material into a container.

close-up of garnets


Dr Jonathan Hare, Physics Dept., The University of Sussex
Brighton, East Sussex. BN1 9QJ

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