Opal - Mineral Specimen green crystal similar to how cave formations

similar to how cave formations develop but on a mineral scale

and also filter feeders

4mmHead Length: 13mmShaft Diameter: 2

I often cut the bristles with scissors on bristle brushes to help them fit in tighter areas

Approximate Width of 1 piece: 1

Opal - Mineral Specimen green crystal similar to how cave formationsMined from: Coober Pedy, South Australia, Australia Description: This Australian opal is shown in rough form, still partially embedded in its host rock, with a mix of pale blue grey translucent silica and earthy red brown ironstone staining. The surface shows natural weathering and pitting, with areas of exposed opal displaying a waxy to slightly glassy luster. Subtle internal color shifts are visible in the cleaner sections, with faint hints of blue