From Wiktionary, the free dictionary
Borrowed from Andalusian Arabic, from Arabic سَبَج (sabaj, “jet”).
zebech m (plural zebeches)
- jet (lignite)
c. 1250, Alfonso X, Lapidario, f. 76v:DEl quarto grado del ſigno de capricornio es la piedra aque llaman zebech. Dura es. ⁊ de color mui negro. ⁊ liuiana de peſo.- Of the fourth degree of the sign of Capricorn is the stone they call jet. It is hard, and of a very black color, and light in weight.