Chalkstone
Outcroppings of this very soft, easily powdered, sedimentary rock with a high calcium carbonate content are found in various parts of Palestine. Because it is worthless as a building stone and can be so readily crumbled and pulverized, the prophet Isaiah used chalkstone in an effective simile to show what must be done to the idolatrous altars of Israel if forgiveness was to be attained. (Isa 27:9) The Aramaic equivalent of the Hebrew term gir (chalk) occurs in Daniel 5:5 and is translated “plaster.”—See LIME; PLASTER.