Minerals

Limestone and dolostone host sulphides and sulphates in fractures and pores within the rock, often forming important mineral reserves. A particular type of mineralization, Mississippi-Valley type, occurs almost exclusively within limestone and dolostone. These deposits are mined in the USA and Canada, but historically have also been important in the UK and Ireland. Here a number of different sub-types have been mined for lead (from galena, PbS) until the 19th Century. In the 20th Century, mining of associated minerals that had historically been of low economic value became more important. For example, in Derbyshire, UK, the fluorite (CaF2) was mined to source fluorine for refrigeration systems and barite (BaSO4) was produced for the manufacture of drilling muds for the oil and gas industry in the North Sea.