This unique Boulder Opal pendant is what is known as pipe opal. Pipe opal is formed by tubes or pipes of opal occurring in the sandstone. The theory is that type of opal formed millions of years ago when organic matter, such as twigs and leaves , disintegrated leaving cavity’s that the liquid opal has filled. This natural formation allows us to create gorgeous unique organic opal jewellery. This opal pendant has aqua, pink and gold colours sparkling from the natural tan coloured sandstone, it measures 42mm long x 30mm at the widest and comes with a waxed cotton necklace with slip knots to adjust the length so the pendant will suit everybody.