From protolith + -ic. <span class="searchmatch">protolithic</span> (not comparable) Relating to a protolith....
+ -lith. (US) IPA(key): /ˈpɹoʊ.təˌlɪθ/ protolith (plural protoliths) (geology) The original precursor of any specified metamorphic rock <span class="searchmatch">protolithic</span>...