From Earth to Elegance: How Australian Opals Are Formed and Mined

Unearthing a Natural Wonder: How Opal is Formed and Mined in Australia
By Sonya Lorenz Gems

Opal, Australia’s national gemstone, is as fascinating beneath the surface as it is on display. Known for its mesmerising play of colour, opal is the result of a geological process that takes millions of years—and nowhere does this magic happen more abundantly or ethically than in Australia.

How Opal is Formed

Opal begins as a solution of silica and water. As rainwater seeps through sandstone, it dissolves silica and carries it into underground cracks, cavities, and the fossilised remains of ancient creatures. Over time, as the water evaporates, tiny silica spheres are left behind. These spheres gradually stack into layers—sometimes trapping water between them—and eventually form opal.

The unique colours we see in precious opal are the result of light diffracting through these microscopic spheres. Smaller spheres reflect cooler tones like blue and green, while larger ones produce rare flashes of orange and red. Remarkably, it can take millions of years to form just a single centimetre of opal.

Where Opal is Found

Australia is responsible for over 90% of the world’s opal production, and at Sonya Lorenz Gems, we are proud to specialise in ethically sourced Australian opals. The most iconic opal fields include:

Coober Pedy (SA): Famous for white or light opal.

Lightning Ridge (NSW): Known for prized black opal.

Andamooka & Mintabie (SA): Producers of matrix and crystal opals.

Queensland: Home to unique Boulder opals, formed in ironstone.

These regions were once part of a vast inland sea, which helped create the ideal conditions for opal formation in ancient sedimentary rock.

How Opal is Mined

Historically, opals were mined by hand using picks, shovels, and manual winches. Today, the process is more refined but still retains its small-scale, independent character. Modern miners drill narrow shafts into opal-bearing layers, then use jackhammers or excavators to extract the stone. Both underground and open-cut methods are used depending on the terrain and regulations.

Once the material is brought to the surface, it’s washed and sorted to separate precious opal from host rock. Even discarded mine tailings may be searched—a practice called noodling—as opal fragments are sometimes missed in the first round.

At Sonya Lorenz Gems, we carefully select opals sourced from these authentic Australian fields. Each gem carries with it the story of the land—formed over millennia, unearthed with care, and ready to be treasured for generations.