Hydraulic brecciation

Hydraulic brecciation

Bryn y Rafr mine, West Wales. Typical brecciated material from this site, which is a mix of host rock, Quartz, and Sphalerite. The host rock is a fine grained dark mudstone. Brecciation is the result of inwardly exploding walls of deep fractures when there is a sudden decrease of pressure in the hot mineral rich fluids which are circulating through the fracture.