*toadstone*

n. 1. (Min.) A local name for the igneous rocks of Derbyshire, England; -- said by some to be derived from the German todter stein, meaning dead stone, that is, stone which contains no ores. [ 1913 Webster ]

2. Bufonite, formerly regarded as a precious stone, and worn as a jewel. See Bufonite. [ 1913 Webster ]