by Siobhan Fraser - 14:05 on 28 December 2015
If you’re ever lucky enough to visit New Zealand, make sure you fit in a trip to Wai-O-Tapu. This is an excellent way to see some of the effects of geothermal activity in action. This pool got its name from the abundant efflux of carbon dioxide – which is very similar to a glass of bubbling champagne. But that’s where the similarities with champagne stop – you certainly wouldn’t want to drink the water from here! The water is geothermally heated to approximately 73 – 75oC. And if that hasn’t put you off, then there are traces of gold, silver, mercury, arsenic and antimony in the water. So where has the distinctive orange edge come from? Well, that’s due to two sulphides of the arsenic – realgar and orpiment. These are in real sharp contract to the grey-white silica sinter that surround the pool.