yeas it is a mineral . yours is from eastern France 1890s or so . though most of this are from Germany, France also produced them up to the 1920. some may be even made over there to this day!
I dug a bunch of these (or similar) broken along with a bunch of broken stoneware quart size Ginger beers in a 1860's Privy so I know they can come from that time frame. LEON.