The Champagne Pool, Wai-O-Tapu, Rotorua, New Zealand

“This spring is the largest in the district, being 65m in diameter and 62m deep. Its surface temperature is 74°C and bubbles are due to carbon dioxide. The pool was formed 700 years ago by a hydrothermal eruption, the rocks from which can be seen at the top of the embankment by the track. Minerals contained in the water are gold, silver, mercury, sulphur, arsenic, thallium, antimony, etc. and are presently depositing in the surrounding sinter ledge.

Beneath the ground is a system of streams which are heated by magma left over from earlier eruptions. The water is so hot (temperatures of up to 300°C have been recorded that it absorbs minerals out of the rocks through which it passes and transports them to the surface as steam where they are ultimately absorbed into the ground. The so-called “rotten egg smell” of geothermal areas is associated with hydrogen sulphide.

The wide range of colours in the area are all natural and are due to different mineral elements. In The Champagne Pool: green- colloidial sulphur/ferrous salts, orange- antimony, red-brown- iron oxide.”

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