obsidian

Etymology

From Latin obsidianus; named after Obsidius, who was, according to Pliny, the Roman who discovered the stone in Aethiopia.

noun

1. (mineralogy) A type of naturally occurring black glass produced by volcanoes.
   The Neolithic culture from 8000 to 6000 B.C., however, was a brilliant period of the revival of crafts, the transformation of gathering into gardening, the growth of a cross-cultural obsidian trade, and the rise of towns. 1981, William Irwin Thompson, The Time Falling Bodies Take to Light: Mythology, Sexuality and the Origins of Culture, London: Rider/Hutchinson & Co., page 130
2. A slightly bluish black, the color of obsidian glass.
   obsidian:

adj

1. (poetic) black