Mt Hay Gemstone Tourist Park
Posted on October 30th, 2019
Mt. Hay is the remains of an extinct ancient volcano, which was last active about 120 million years ago. When it was a rumbling volcano millions of gas bubbles were present in the molten rhyolite lava .. it is these gas ‘pockets’ that became thundereggs. Thundereggs or volcanic birthstones are the result of these ‘pockets’ filling with siliceous liquids containing impurities and trace elements, which crystallize as they cool, and when cut in half, reveal many different colours and patterns.