rhyolithic

From German Rhyolith (“rhyolite”) + -ic, presumably under influence from -lithic.

rhyolithic (comparative more rhyolithic, superlative most rhyolithic)

1. (obsolete) Alternative form of rhyolitic: composed of or related to rhyolite.
   • 1864, Friedrich von Hochstetter et al., translated by Carl Franz Fischer, Geology of New Zealand, page 55:

     The eruptive masses of the Taupo zone consist of lava (the richest known) of silicious earth, also of rhyolithic rocks of all kinds.

   • 1884, "St Paul" in the Encyclopaedia Britannica, 9th ed., Vol. XXI, p. 189:

     According to M. Vélain, the island originally rose above the ocean as a mass of rhyolithic trachyte similar to that which still forms the Nine Pin rock to the north of the entrance to the crater.

• “rhyolitic, adj.”, in OED Online ⁠, Oxford, Oxfordshire: Oxford University Press, 2010.