'silicious' originates from Latin roots, ultimately from Latin 'silex, silicis' meaning 'flint' or 'hard stone', with the English adjectival suffix '-ous' appended.

'silicious' developed via New/Late Latin and Modern Latin formations (compare Latin 'siliceus' and Medieval/Neo-Latin forms) into English; it parallels the formation of 'siliceous' and other silica-related adjectives.

Initially it referred to matter 'of or relating to flint or silica', and over time its usage has remained essentially the same: 'containing or composed of silica'.