1. (Science: botany) a kind of glass, containing gold-coloured spangles. It was produced in the first place by the accidental (par aventure) dropping of some brass filings into a pot of melted glass.
2. (Science: chemical) a variety of translucent quartz, spangled throughout with scales of yellow mica. ~ feldspar, a variety of oligoclase with internal firelike reflections due to the presence of minute crystals, probably of hematite; sunstone.
Origin: f. Aventurine: cf. It. Avventurino.