en.wikipedia does say: > Other raw materials can include feldspar, ball clay, glass, bone ash, steatite, quartz, petuntse and alabaster. So I'd guess that "Po

en.wikipedia does say: > Other raw materials can include feldspar, ball clay, glass, bone ash, steatite, quartz, petuntse and alabaster. So I'd guess that "Porcelain Stone" isn't anything specific, but could possibly (not even necessarily) be a silicate.