The Variscite Collection

How Variscite Formed in the Gascoyne

Some of the rock in Western Australia's Gascoyne region is over 1.6 billion years old. Here's how it ended up holding thin seams of bright green stone, and gold in the ground around it, and why there's so little of either.

Rough Australian variscite in its natural form, showing bright green banding through the raw stone — Rough variscite, exactly as it comes out of the ground in the Gascoyne. The green rarely runs deep or wide, which is most of why this stone is hard to find in any quantity.

1.68–1.46Byears old, the age of the host rock

150ppmpeak native gold found in the same ground

1970sdecade small-scale mining began

01Rock from before almost anything else

The Gascoyne region of central Western Australia sits inside the Capricorn Orogen, a vast ancient belt of crust wedged between two of the oldest surviving pieces of continent on Earth, the Pilbara Craton to the north and the Yilgarn Craton to the south.

Somewhere between roughly 1.68 and 1.46 billion years ago, in the Mesoproterozoic, a shallow sea moved across part of this region and began laying down sediment: siltstone, sandstone, dolomitic siltstone, stromatolitic dolomite, in places building up more than four kilometres thick. Geologists call this the Edmund Basin, and it's some of the oldest rock anywhere on the continent still holding a gemstone.

Remote variscite mining site in the Gascoyne region of Western Australia, showing the sparse outback landscape where the deposits are worked — The Gascoyne, where the deposits sit. Small-scale, remote, and a long way from anything else. Photo courtesy of our mining partner.

02How the green got into the cracks

Variscite doesn't form all at once. It's what's known as a secondary mineral, meaning it forms much later than the rock around it, when groundwater moving through rock that already exists reacts chemically with what's there.

Around Mount Deverell, the source region for most Western Australian variscite, phosphate-carrying groundwater moved through that billion-year-old Edmund Basin shale and mudstone, near the surface rather than deep underground. Where that water met the aluminium already present in the rock, it deposited variscite, an aluminium phosphate, directly into cracks, hairline fractures and small cavities. It isn't one continuous seam. It's narrow veins, most only millimetres wide, following whichever fracture gave the water somewhere to sit and precipitate.

The same ground holds more than green stone. Deeper in the weathering profile beneath the variscite, native gold has been documented here too, up to around 150 parts per million at its richest. It isn't inside the variscite itself, the two formed through the same slow chemical process in the same rock, but as separate minerals, not one. Still, it means this small patch of the Gascoyne has quietly produced two valuable things, not one.

The green itself comes down to a trace amount of chromium locked into the mineral's structure. More chromium generally means a deeper, richer green.

Close-up of a thin green variscite vein exposed in the rock face, running through layered orange and rust-coloured host rock — A variscite vein exposed mid-dig. This is exactly the scale it forms at: a thin green line, not a boulder. Photo courtesy of our mining partner.

03Often mistaken for turquoise, for good reason

Variscite and turquoise are close chemical relatives. Both are hydrated aluminium phosphates, and at Mount Deverell they've actually turned up in the same deposit, alongside other secondary phosphate minerals like collinsite and gordonite.

The real difference between them is copper. Turquoise needs it as an essential ingredient; variscite has none. That absence is a large part of why variscite tends to read as a purer, sometimes more vivid green, while turquoise leans more blue. It also means variscite is noticeably softer, roughly 4.5 on the Mohs scale against turquoise's 5 to 6, which is exactly why we handle it carefully at the cutting bench and don't recommend it for a piece that's going to take a daily beating.

Two miners hand-digging for variscite in a small open pit in the Western Australian outback, with an excavator standing by — Once the machinery clears the overburden, the last of it is still done by hand. Photo courtesy of our mining partner.

What that means for the stone in your hand

Every piece of variscite we set has been through two very different timescales. The rock around it sat in the ground for over a billion years, long before there was complex life on land, before it ever had the chance to hold anything green. And the mining itself has stayed small and slow since it began in the 1970s, narrow veins worked by hand in a remote part of Western Australia. There was never going to be much of this stone, and there still isn't.

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Hand-cut Australian variscite, set in our interchangeable bezel system. Every stone carries this same story.

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