Australian Boulder Opal Specimen – Rough Ironstone, Green & Blue Opal Seam

A large, rugged boulder opal specimen from Queensland, left in its natural rough state except for a single window cut and polished along one face. That window reveals a continuous horizontal seam of vivid green and blue opal running the full length of the stone, sandwiched between darker ironstone layers above and below. The rest of the exterior keeps its raw, weathered ironstone texture — cracked, earthy and reddish-brown — so the piece reads as a genuine chunk of the opal field rather than a cut gem, with the colour play left as a striking exposed vein through the rock.

About Boulder Opal

Boulder opal forms as veins of precious opal within ironstone matrix in the opal fields of Queensland — primarily Quilpie, Yowah and Winton. Unlike black opal from Lightning Ridge, the opal cannot be separated from its host rock; it's cut as a single solid piece, with the natural brown ironstone remaining as the stone's backing. This gives boulder opal its distinctive look — vivid colour against rich earth tones — and also makes it physically more durable than other opals, since the ironstone host is harder than the opal layer it carries.

Specifications

• Stone: Boulder Opal in ironstone matrix
• Dimensions: Length 22cm × Height 10cm × Width 10cm
• Weight: 2.9kg
• Finish: Natural rough exterior with one polished opal face
• Matrix / Host Rock: Ironstone
• Origin: Queensland, Australia
• Availability: One-of-a-kind — 1 piece available

Caring for Your Opal

Boulder opal is more durable than other opal types because the ironstone matrix backs and protects the opal seam, but it's still best displayed away from direct sunlight and prolonged heat, which can affect the opal layer over time. Handle by the ironstone body rather than the opal seam itself. Dust with a soft, dry cloth; avoid ultrasonic or steam cleaners and prolonged soaking. See Opal Care for the full routine.

Provenance

Hand-selected by Joseph Bernecki, sourced direct from the Australian opal fields and set in his Sydney workshop. Meet him any weekend at The Rocks Market, stall under the bridge, Sydney. Read Joseph's story →

Common Questions