This piece of Koroit boulder opal is a section of an opal nut. They are round like a nut, with colour in different places. This piece of Koroit boulder opal is in nut form with a line of colour running around it like a band.
This rough opal has hints of purple and flashes of green. It is a pretty piece at a low price. It came from a jar of opal I picked up from the Two Skies guys at the gold panning championships.