boulder opal

noun

An opal consisting of concretions and fracture fillings in a dark siliceous ironstone matrix.

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Meanings

nounboulder opal (countable and uncountable, plural boulder opals)

plural boulder opals

  1. countableuncountableAn opal consisting of concretions and fracture fillings in a dark siliceous ironstone matrix.
Cite this entry
APA

boulder opal. (n.d.). In WatkinsX Dictionary. Retrieved November 3, 2026, from https://dictionary.watkinsx.com/word/boulder%20opal

MLA

“boulder opal.” WatkinsX Dictionary, https://dictionary.watkinsx.com/word/boulder%20opal. Accessed November 3, 2026.

Chicago

WatkinsX Dictionary, s.v. “boulder opal,” accessed November 3, 2026, https://dictionary.watkinsx.com/word/boulder%20opal.

Source: boulder opal on Wiktionary, CC BY-SA 4.0.