local. [Of uncertain origin; thought by some to be so named from the resemblance of its amygdaloidal spots to those on a toad’s skin; by others to be a corruption of a Ger. todtes gestein ‘dead rock,’ reduced perh. to *todt-stein. But there appears to be no evidence of this, other than the fact that some Derbyshire mining terms appear to be of German origin.] A name given by the Derbyshire lead-miners to an igneous rock, occurring as irregular sheets of contemporaneous lava, interstratified with, or in connection with the metalliferous mountain limestone.
1784. Darwin, in Phil. Trans., LXXV. 5. The vast beds of toad-stone or lava in many parts of this country.
1796. Kirwan, Elem. Min. (ed. 2), I. 229. Toadstone is of a dark brownish grey colour, abounding with cavities filled with crystallized spar.
1823. G. Chalmers, Caledonia, III. II. iii. 52. The rock is covered occasionally by toadstone, called in that country coppercraig.
1859. Page, Handbk. Geol. Terms, 355. Some of these toadstone beds are compact and basaltic, others are earthy, vesicular, and amygdaloidal.
1888. Derbysh. Archæol. Soc. Jrnl., X. 2. The white patches of calcite give to a freshly fractured surface of the rock a peculiar appearance,… considered so like the marks on the body of a toad that the rock is known as Toadstone.
