Meaning

noun a translucent quartz spangled with bits of mica or other minerals

originBorrowed from French aventurine, from Italian avventurino, from avventurare (“to venture; to make lucky or prosperous”), from avventura (“chance; adventure, venture”) + -are (suffix forming the infinitive of most regular verbs), apparently so named because it was discovered by accident in Murano, Italy, when brass or copper filings were dropped into melted glass (see, however, the 1843 quotation).

Etymology from Wiktionary, CC BY-SA 3.0