What is "mundic"

Mundic \Mun"dic\, n. Iron pyrites, or arsenical pyrites; -- so called by the Cornish miners.

n. (context mining UK dialect Cornwall English) iron pyrite or arsenic pyrite

Mundic was used from the 1690s to describe a copper ore that began to be smelted at Bristol and elsewhere in southwestern Britain. Smelting was carried out in cupolas, that is reverberatory furnaces using mineral coal. For more details, see copper extraction.

Mundic once referred to pyrite, but has now adopted the wider meaning of concrete deterioration caused by oxidisation of pyrites within the aggregate (usually originating from mine waste). The action of water and oxygen on pyrite forms sulphate (a salt of sulphiric acid), thereby depleting the pyrite, causing loss of adhesion and physical expansion.