Rocks / Hydraulic Breccia

This type of brecciation occurs deep underground when hot hydrothermal fluids within a fracture exert terrific pressure on the walls of the fracture, which forces the walls apart .If the pressurised, contained fluid finds an escape route there is an instataneous release of pressure on the walls of the fracture, which shatter and implode fragments of wall rock into the fluid.  The fluid eventually cools and solidifies, creating examples such as this specimen. The shattered fragments don't move a great distance as can be observed in the inset picture. The specimen was collected from Dylife mine in Powys.

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