Nebula Chalcedony Cluster - Western Sahara, Morocco
This listing is for one, sold as seen, unique specimen of Nebula Chalcedony from the Western Sahara region, Morocco.
Dimensions: approx. 3.5cms x 3.2cms x 2.5cms
Weight: 25g
The nebula chalcedony labelled from Western Sahara, Morocco is primarily sourced from the world-famous Bu Craa, open-pit phosphate mines, which famously produce a unique "truffle" or "nebula" chalcedony. These Western Sahara specimens are entirely unique from other volcanic gas bubble chalcedony variants found in Mexico or the USA, as these, Western Sahara nebula chalcedony clusters are actually ancient, fossilized marine sponges that were replaced over millions of years by microcrystalline quartz and are often mis-labelled as “formed by volcanic activity”.
Between 50-75 million years ago, the area that is now the dry Sahara Desert was a warm, shallow ocean that sat over the Tarfaya/Dakhla sedimentary basin. Millions of tiny, silica-framed marine organisms and colonial sea sponges died and sank to the sea floor and over time their organic remains mixed with mineral-rich sediment, forming a thick layer of phosphate-rich rock (which is exactly what the Bu Craa mine excavates today).
As the sediment compacted, cold groundwater squeezed through the layers, dissolving the microscopic silica shells on the sea floor, creating a rich silica gel. This fluid slowly dripped into the hollow spaces left by decaying sea sponges, replacing them molecule-by-molecule with layered chalcedony before the rock fully dried out. The smoky, grey-brown tint is caused by natural radiation from the surrounding phosphate-rich sediment emitting tiny, harmless amounts of natural background radiation over millions of years, altering the crystal lattice of the clear silica, causing it to absorb light and turn a "smoky" hue and from, micro-particles of organic carbon and manganese from the ancient sea sponges became permanently trapped between the growing quartz fibres, acting like a natural tint.
These particular specimens will fluoresce under UV light with reddish orange glow.
**Please Note: Fluorescent images have been taken with a smart phone and unfortunately their internal software is built to automatically "fix" low-light environments, which completely ruins the pure, raw light data of UV fluorescence and so photograph is not of the best quality or necessarily a true reflection of the stones fluorescence.**