Geology

The Waihi landscape was very different seven million years ago. The land was higher, probably by several hundred metres. Geysers threw boiling, mineral rich water high into the air, mudpools bubbled and hot springs dotted the countryside, very much like Rotorua today. Hot rock far below the ground provided heat energy for those spectacular features and also provided the ingredients for the gold deposit to be formed at Martha Hill. Over time the volcanic activity dwindled in the Waihi area as gradual movement in the earth's crust meant the volcanic 'hot spot' was felt through Tauranga, then Te Puke, to be centred around Rotorua today.

This volcanic activity provided the conditions and environment for the gold and silver now being mined in Waihi.

A recipe for gold

Volcanic violence Around 20 million years ago volcanoes burst through the landscape around what we now know as Waihi. Tall, steep sided andesite volcanoes formed as the hot lava was thrown out to coat the sides of the volcanoes and the surrounding land. These volcanoes...more »

Geology of the Waihi area

Millions of years ago, during the Miocene Period, a thick sequence of volcanic lavas, breccias and tuffs of generally andesitic composition was deposited to form the bedrock of Waihi and surrounding districts. Some considerable time later earthquake activity formed numerous near-vertical planar fractures in the...more »

Geology at the waste rock embankments

The waste rock embankment site basement geology comprises predominantly rhyolite, with some dacite. Rhyolite forms the steep hills to the east of Storage 2 and all of Storage 1A. It grades from a completely weathered clay-rich surface to an unweathered rock. Dacite forms Black...more »