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Geology and ore deposits of the mines

Mynydd Parys is an area of complex geology which is still under investigation. The rocks consist of an isolated series of volcanic intrusions and lavas, ashes and muds, laid down in a sea some 440 million years ago.
( the Ordovician/Silurian Boundary )

The mineralisation originated as deposits on the sea floor from hot fluids associated with the volcanic activity, as has been observed as "smokers" in our present oceans. This "KUROKO" type of mineralisation at Mynydd Parys is unique in the UK. Later the strata were tilted and folded, and some of the metals were redistributed to give the complex ore deposits that have been exploited in the Mona and Parys Mines.

The ores contain copper, lead, zinc, and abundant iron, together with traces of gold, silver and other rare metals.

The main ore minerals at the mountain include :-

Chalcopyrite - a mixed copper-iron sulphide ( CuFeS2 )
Sphalerite - Zinc-Sulphide ( ZnS )
Galena - Lead-Sulphide ( PbS )

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