Opake

Gestures […] are not of general use, since darkness or the interposition of an opake medium renders them useless.

The artificial marble made here is made in the common way with Gypsum Lime and other materials and the artist who is an Italian calls himself a Scagliolist (Scagliola being their name for Gypsum or works in Gypsum) he imitates some of the opake and coloured marbles […]