A mineral consisting of a double carbonate of calcium and barium, typically occurring as strongly striated colourless or white pseudohexagonal pyramids.
Chemical formula: BaCa(CO₃)₂. Crystal system: triclinic.
Mid 19th century; earliest use found in Edinburgh New Philosophical Journal. From the name of AlstonMoor, an area of moorland in Cumbria, England, where the mineral was discovered + -ite, after German Alstonit.