ἐν πέτροισι πέτρον ἐκτρίβων → by grinding stone against stones
trĭlībris: e, adj. ter-libra,I of three pounds weight, three-pound-: mullus, Hor. S. 2, 2, 33: paterae, scyphi, Gall. ap. Treb. Claud. 17.
