A narrowing in a vein of ore, rendering it less profitable. To Pinch. To contract.
1869. They know that it [the lead] may cap, or pinch, or play out entirely.—A. K. McClure. ‘Rocky Mountains,’ p. 267.
1878. Again he [the miner] encounters a “pinch” or “cap,” and hope almost dies out ere he gets through it.—J. H. Beadle, ‘Western Wilds,’ p. 486.
