How is Rotorua’s Famous Thermal Mud Formed?

From Volcano to Skincare — The Science Behind Thermal Mud

Thermal mud begins deep underground in high-temperature geothermal areas, often near volcanoes (active or long dormant). Steam and mineral-rich gases rise up from the earth and enter rainwater ponds. These gases, often slightly acidic, break down surrounding rock into fine clay. This clay blends with the hot water, creating a thick, mineral-rich slurry; what we know as thermal mud.

In Rotorua’s geothermal fields, you’ll notice that the mud is constantly bubbling and popping. This is thanks to hydrogen sulphide gas; the same gas that gives Rotorua its famous “rotten egg” aroma. While the smell might be memorable, it’s also a sign of the mineral-rich environment that makes Rotorua thermal mud so special for the skin.

How Weather Changes Mud Pools

• Dry weather: The mud thickens, forming sticky, paste-like textures with small “mini volcano” mounds.
• Rainy days: The mud becomes more fluid, looking almost like boiling hot chocolate (though we definitely don’t recommend tasting it!).

Fun Fact:

Some mud pools in Rotorua have been bubbling for hundreds — even thousands — of years, fed by underground heat from the Taupō Volcanic Zone.

Why Rotorua Thermal Mud is a Skincare Superhero

Not all thermal mud is the same. The exact blend of minerals and trace elements depends on where it’s found — from New Zealand to Hawaii, Italy, or Japan, each volcanic region creates a unique mineral profile.

Rotorua Thermal Mud is rich in silica, magnesium, calcium, sulphur, potassium, and other natural minerals. These work together to:

• Deep cleanse by drawing out oils, dirt, and impurities
• Detoxify the skin naturally
• Nourish with replenishing minerals
• Relax both skin and senses

That’s why at Pure Source, we celebrate this ingredient in our masks, skincare, and scrubs — giving your skin a taste of Rotorua’s natural spa therapy, wherever you are in the world.

Our tip: Your skin loves a little dirt — especially when it’s mineral-rich Rotorua mud.