Black opal price
- how is black opal formed
- how is black opal made
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Biggest opal ever found.
How is Opal Formed?
The Geology of Opal
FAQ : How is opal formed?
How is opal formed/ How are opals formed? What is the Great Artesian Basin? What is potch? What causes the formation of opal?
A Simple Explanation
Opal is formed from a solution of silicon dioxide and water. As water runs down through the earth, it picks up silica from sandstone, and carries this silica-rich solution into cracks and voids , caused by natural faults or decomposing fossils.
How long does it take for opal to form
As the water evaporates, it leaves behind a silica deposit. This cycle repeats over very long periods of time, and eventually opal is formed.
Visualise the inside of an opal, like a bag of marbles. The marbles are the silica spheres.
Smaller spheres are more commonly forming, and tend to defract the purple/ blue/ green colours.
Larger spheres are rarer forming, and tend to show off the yellow/ orange/ pink and red colours.
Hence why these are the rarer colours to find in Australian Opal.
A Detailed Explanation
Occasionally, when conditions are ideal, spheres of silica, contained in silica-rich solutions in the earth form and settle under
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