Emily Dickinson Lexicon

PUM'ICE, n. [L. pumex, supposed to be from the root of spuma, foam; G. bimstein; D. puimsteen.]

A substance frequently ejected from volcanoes, of various colors, gray, white, reddish brown or black; hard, rough and porous; specifically lighter than water, and resembling the slag produced in an iron furnace. It consists of parallel fibers, and is supposed to be asbestos decomposed by the action of fire. – Encyc. Nicholson. Pumice is of three kinds, glassy, common, and porphyritic. – Ure.