The Kilaueu volcano on Hawaii's biggest island has been erupting almost continually since 1983, but in May 2018 this activity significantly increased in ferocity. The event has brought with it a rare and fascinating geological event that has seen people finding crystals of Olivine (also known as Peridot when at gem quality) on the ground around the volcano.
Most gems form in the earth's crust, but Peridot forms so deep in the earth, in the mantle, that for us to be able to mine the gem it needs to be brought closer to the surface by some other force. That force is provided by tectonic and volcanic activity. In very simplistic terms, the force of tectonic plate movement and lava being forced to the surface from deep within the earth is great enough to carry a huge amount of material with it, and either blast it out onto the surface or deposit it near enough to the surface that it can be mined traditionally. These rocks often contain the mineral Olivine, which is known at Peridot when it occurs in gem quality specimens. The only other gemstone to form so deep and under such hostile conditions, is Diamond.
What's happening in Hawaii as part of the eruption of the Kilauea volcano is incredibly rare but it's this exact process in living motion. At the beginning of June 2018 residents on the island that live near the volcano started reporting finding little green stones on the ground. Closer analysis had shown these to be Olivine. The force of the volcanic eruptions blows apart chunks of magma, often separating the Olivine from the rest of the ejectamenta and essentially 'raining' Peridot down on the surrounding area. The mineral is not formed by this process, but has been carried to the surface and ejected from the volcano in the lava, which has then cooled into the recognisable green gem.
It's not uncommon to find Olivine and Peridot in the cooled lava flows on Hawaii after a volcanic event such as this. In fact, it's so common on the island that Papakolea Beach, at the southern point of Hawaii's big island, boasts an incredible green-tinted beach that has been coloured by the prolific Olivine in the rocks. Coastal erosion frees the green mineral from the rocks, then washes tiny crystals back onto the shore where it becomes part of the sand. This is one of only four green sand beaches in the world.
What is extremely uncommon (but not unheard of) in this situation is the way the sudden and forceful blast of lava, travelling up to 130 feet into the air, is being cooled rapidly as it escapes from beneath the earth and settles on the surface. This can expose the Olivine crystals and even separate them from the rest of the liquid rock. On top of this, as the lava crawls across the land, bits of rock are being 'spat' out of the flow and deposited on the ground. The sheer power of the lava is unfathomable. It began to flow into Hawaii's largest freshwater lake on Saturday June 9th, and before the end of Sunday June 10th the entire lake had been boiled to evaporation - vaporised.
Olivine is reportedly also being found as larger pieces of the rapidly cooled lava rock are being trodden on or driven over by cars, or simply breaking apart as they hit the surface, freeing the mineral. Several people tweeted pictures of some of the stones that have been found by the locals, which show just how large and colourful some of these newly ejected Peridot crystals are. It's an awe-inspiring act of nature that shows the phenomenal forces at play in bringing us some of our favourite gemstones. Brand new land is being created where the lava is flowing into the sea and cooling too, so Hawaii is just a little bit bigger than it was before the event.
We hope you enjoyed reading about this highly unusual geological event. You can learn more about beautiful golden green Peridot here.
We stock a wonderful range of jewellery designs featuring Peridot from some of the planet's finest sources, though none recently ejected from a volcano! Want to add Peridot to your jewellery collection? Click here.