A Beginner's Guide to OPAL - Part 5 Types of Opal

Australianopaldirect09 Oct, 2022Business

During the Cretaceous period (65?140 million years ago), the deserts were an inland sea teeming with life. The sea gradually receded and laid the foundations of the silica that would form today's opal. During the mid-Tertiary period, changes in Earth's climate caused quantities of soluble silica to be released from the sediment, which found its way down through cracks and faults and eventually hardened over time. This hardening continued to form the common and expensive opal.