A protolith (from Ancient Greek πρωτο (prōto) 'first' and λίθος (líthos) 'stone') is the original, unmetamorphosed rock from which a given metamorphic rock is formed.
Identifying a protolith is a major aim of metamorphic geology.
The source of the sediment of a sedimentary rock is termed its provenance.
Similarly, sedimentary protoliths can be classified as quartzo-feldspathic, pelitic, carbonate rocks, or some mixture of the three.
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