It might have participated in some great Shakespearean insults – if only it had come into its own just a couple of centuries earlier.
In the late 18th century, schist (a layered type of metamorphic rock) was hewn from the earlier schistus, modified at the beginning of the 17th century from le French, schiste.
The French had broken up Latin’s schistos lapis (“stone that splits easily”~ Pliny), in turn derived from Greek skhistos (divided, separated) – originally a chip of their ol’ skhizein (to split).