(obsolete) lapis infernalis, lunar caustic / (obsolete) caustic potash

A stone laid during the construction of a (usually important) building, the laying of which is usually marked by a ceremony. / (figuratively) The basis of something.

A hammer formed with a face at one end, and a thick, blunt edge, parallel with the handle, at the other, used for breaking stone.

An echinite.

A kind of crust deposited in wine casks; crude argol.

(obsolete) An imitation jewel or precious stone.

plural of foil stone

crystal ball

A primitive method of boiling water or milk by dropping hot stones into it.

A perpend. / A flat gravestone.