Area: 0.3 hectares.
Description and Reasons for Notification:
The site consists of a mine dump resulting from the working of the largest sulphide lode in south-west England – a vein which was worked for some 4 kilometers, largely for copper.
Most of the other dumps associated with their vein have been reworked but the present site is relatively untouched and is indicative of the original vein mineralogy. The dump provides fine examples of massive arsenopyrite and “comby” quartz containing well crystallised siderite (iron carbonate) and francolite (a variety of apatite). Large blocks of siderite are also plentiful. These carbon-rich ‘gangue’ minerals are typical of veins within the calcareous Upper Devonian rocks but are rarely associated with mineralisation elsewhere in south-west England.
As most of the copper has been removed, and the arsenopyrite is resistant to weathering, there are few secondary copper/arsenic minerals and the dump thus provides a good example of the primary mineralisation of the area.