Pounamu, also known as New Zealand greenstone, is a type of rock called nephrite jade. It’s found mostly in Te Waipounamu, the South Island, especially on Te Tai Poutini, the West Coast. Pounamu is one of the hardest and toughest stones in the natural world.
Pounamu is one of the hardest and toughest stones in the natural world. Image: LEARNZ.
How was pounamu formed?
Millions of years ago, deep under the earth, heat and pressure from colliding tectonic plates caused special minerals to be squeezed and heated over long periods of time. This slow process created a dense, strong rock – nephrite jade – known in Aotearoa as pounamu.
Te Waipounamu sits along the Alpine Fault, where the Pacific and Australian tectonic plates meet. This fault zone provided the perfect conditions for pounamu to form underground.
Over time, the mountains rose, and rivers carved through the rock, breaking pieces of pounamu off and washing them down into riverbeds. That’s why you often find pounamu in or near rivers and streams, not just in mountains.
Pounamu is often found in or near rivers and streams, not just in mountains. Image: LEARNZ.
What makes pounamu so special geologically?
- It’s incredibly strong and tough. Pounamu is much harder than ordinary rock – that’s why it was perfect for making tools and weapons.
- It has a smooth, waxy texture when polished.
- It’s full of fibrous crystals. These tiny crystals are packed together in a way that makes the stone very difficult to break.
Types of pounamu
Geologists and Māori both recognise different types of pounamu, depending on their mineral makeup, colour, and pattern. Most pounamu is a type of nephrite, but some special varieties include:
- Bowenite – A related mineral often called tangiwai, which is slightly softer and glassier in appearance.
- Serpentine – A common mineral found alongside pounamu, but not the same thing. Serpentine can look similar, but it’s not as tough.
Why is pounamu only found in Te Waipounamu, the South Island?
The unique combination of heat, pressure, and minerals that created pounamu only happened in certain parts of Te Waipounamu, especially on Te Tai Poutini and around Piopiotahi, Fiordland. These regions were geologically active, with the right ingredients to form pounamu over millions of years.
This is why pounamu is considered a taonga tuku iho of Te Waipounamu, and why Ngāi Tahu have been the kaitiaki for generations, up to the present day.
Māori kupu | key words
taonga tuku iho | a treasure passed down
kaitiaki | guardians
Te Tai Poutini | the West Coast
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