Oh, Kilauea. Blue fire, volcanic tornadoes, baby volcanic cone building, and the violent vaporization of the island’s largest lake – what’s next in your box of flamboyant volcanological wizardry?
Well, as has been reported in a few tweets, it appears that it’s been raining gemstones, specifically olivine, onto the ground. Plenty, including Mashable, have been wondering if this is actually a legitimate process or not. So is it?
The green gemstone you can see here is olivine, an extremely common component of volcanic rocks. This iron-magnesium mineral has its own geochemical spectrum, and comes in plenty of flavors, but they tend to be light green in color and vitreous.
It’s ubiquitous in igneous rocks with a low-silica content, like the sort that’s freshly erupting from Kilauea right now. It’s one of the first things to take solid form within the magma as it begins to cool underground.
In fact, the near-mantle derived magma that’s erupting now is as hot as you can get – around 1,116°C (2,040°F) – which suggests it has a very low silica content. This makes the appearance of plenty of olivine more likely than it did a month or so ago.
Olivine is actually already everywhere in Hawaii. Over time, as this basaltic lava is weathered down, its mineral inclusions fall out, including olivine. In fact, geologist David Bressan and volcanologist Dr Janine Krippner were quick to point out to me on Twitter that there’s an entire beach made of olivine on the Big Island.
An extremely rare sight anywhere in the world, Hawaii’s – Papakolea Beach – formed when olivine crystals eroded out of the volcanic landscape. As these grains are heavier than many others, they remain onshore while others get washed away, which eventually produces a freakishly green beach.
It’s been suggested, though, that olivine is raining down on the landscape. Is this plausible?