Introduction: graphite - native carbon - is a widespread mineral, occurring, for example, as a constituent of organic matter as in black shales. The carbon input to such rocks is provided by the bodies of dead micro- and macrofauna, such as plankton and graptolites: under the anoxic sea-floor conditions under which hemipelagites are formed, the resulting organic matter tends to be preserved and buried within the sediment. It is also commonly found in metamorphic rocks of all grades formed from original sedimentary rocks containing carbonaceous matter. Graphite may also occur in hydrothermal deposits, by the reaction of carbon-bearing compounds with mineralizing fluids. Sulphides, precipitated under the same conditions, are frequent associates, in particular pyrite and pyrrhotite. Graphite is easy to identify in large masses but when fine-grained may be difficult to distinguish from other organic compounds without experience.

Occurrence in Wales: graphite occurs widely in Wales as a fine-grained constituent of hemipelagic marine sedimentary rocks (black shales). Although graphite is widespread as a rock-forming mineral, specimen occurrences are restricted to a single locality.

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