Tintenbar Opal Identification Guide
Identify Tintenbar opal, a rare volcanic-hosted Australian precious opal, by its play-of-color, hydrated silica properties, and basalt host.
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What Tintenbar Opal Looks Like
Tintenbar opal is a rare precious opal from the Tintenbar area of northern New South Wales, Australia. Unlike the famous sedimentary opals of Lightning Ridge or Coober Pedy, it is volcanic-hosted, occurring in cavities and seams within weathered basalt.
- Color: body tone ranges from clear/colorless to milky white, gray, and amber, with vivid spectral play-of-color in fine pieces
- Luster: vitreous to resinous
- Transparency: transparent to translucent
- Form: seam and vein fillings, nodules, and infillings in vesicular basalt
Step-by-Step Field ID Checklist
- Confirm play-of-color — flashes of spectral color that shift as you rotate the stone (precious opal) versus a plain body color (common opal/potch).
- Check the host rock: volcanic opal sits in or near weathered basalt, not in sandstone or ironstone.
- Note relatively low weight in the hand (opal is light).
- Look for a vitreous-to-resinous, slightly waxy surface.
- Be cautious about water: some volcanic opal is hydrophane and changes appearance when wet.
Key Diagnostic Tests
- Hardness: ~5.5–6.5; opal scratches more easily than quartz and chalcedony.
- Streak: white.
- Fracture: conchoidal; no cleavage.
- Density: low, ~1.9–2.2, lighter than quartz — a useful tell.
- Hydrophane behavior: porous volcanic opal may absorb water, becoming more transparent and sometimes losing fire temporarily; this is normal, not a defect.
Common Look-Alikes
- Other Australian sedimentary opal (Lightning Ridge, Coober Pedy): very similar appearance — provenance is established by host rock (basalt vs sandstone/ironstone) and locality records, not by eye.
- Ethiopian (Welo) opal: also volcanic and often strongly hydrophane; chemical/locality data distinguish it, not visual fire alone.
- Opalite / glass imitations: show a uniform bluish floating glow, not true directional spectral play-of-color, and may contain bubbles.
- Common opal (potch): same material but no play-of-color.
- Labradorite: has feldspar cleavage and a metallic schiller (labradorescence), is harder, and is not silica gel.
Where It Is Found
Tintenbar opal comes specifically from the Tintenbar / Ballina district of the Northern Rivers region, New South Wales, Australia, hosted in Cenozoic basalts. It is historically significant as one of Australia's early-recorded volcanic precious opal occurrences and is uncommon on the market.
Frequently asked questions
What makes Tintenbar opal different from other Australian opal?
Tintenbar opal is volcanic-hosted, forming in weathered basalt in northern New South Wales, rather than in the sandstone and ironstone that host most Australian sedimentary opal.
How can you tell if Tintenbar opal is real precious opal?
True precious opal shows directional play-of-color that shifts as you rotate it, has low density (about 1.9–2.2), and a hardness around 5.5–6.5; imitation opalite shows only a uniform bluish glow.
Is Tintenbar opal hydrophane?
Some volcanic opal from the area is porous and hydrophane, meaning it can absorb water and temporarily change transparency or fire; this is a natural property and reverses as it dries.
Where is Tintenbar opal found?
It is found in the Tintenbar and Ballina district of the Northern Rivers region in New South Wales, Australia, within Cenozoic basalt.
Tintenbar Opal identified by the community
Recent Tintenbar Opal specimens identified with Rock Identifier.
