Mining. Obs. [? F. croûte crust.] ‘A substance found about the ore in the lead mines at Mendip, being a mealy, white, soft stone, matted with ore’ (Chambers, Cycl. Suppl.).
1668. Phil. Trans., III. 770. There is Sparr and Caulk about the Ore; and another substance, which they call the Crootes which is a mealy white stone, marted with Ore and soft. Ibid. It terminates in a dead Earth Clayie, without Croot or Sparr.
1759. B. Martin, Nat. Hist. Eng., I. 67.
