This specimen of breccia is from Henfwlch mine, Nant y Moch reservoir, Ceredigion. Angular clasts of wall rock are embedded in a matrix mainly composed of a mineral in the Ankerite/Dolomite series. The brown colour suggests that it is a manesium rich/iron defictent ankerite which is also referred to as ferroan dolomite. This type of specimen is plentiful at this site.