Abstract

Graphite was deposited in and around a diabase intruded along post-Borrowdale Volcanic, pre-Bala faults about 4,000 feet above the Skiddaw Slate-Borrowdale Volcanic boundary. Associated copper-lead-zinc mineralization follows faults of the same trend, and is isotopically dated at 470 million years (mid-Ordovician). The breakdown of carbon monoxide in the magmatic gases was promoted by substances (notably pyrite, iron oxides, iron silicates, and quartz) which catalysed the Boudouard reaction 2CO <--> CO 2 + C. The PT conditions of deposition of the graphite and associated minerals are estimated at P approximately 1,000 bars, T approximately 120 degrees to 600 degrees C. Possible occurrences of natural interlamellar compounds of graphite are discussed.

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