Lewis & Short

pūmĭcĕus, a, um, adj. [pumex],

  1. I. of pumice-stone, or of soft stone; in gen. (very rare): molae, Ov. F. 6, 318: sedes, Sil. 7, 419: antra, Stat. S. 3, 1, 144; cf. fontes, flowing from pumice-stone, Mart. 4, 57, 2.
  2. II. Trop.: oculi, not in a condition to weep, stony, dry, Plaut. Ps. 1, 1, 73.