This is a solid, black opal "picture stone" from Lightning Ridge.
Picture stones are opals where face of the stone forms a unique and interesting shape, form or picture. Like clouds, we may all see a different picture and the picture may change depending on the orientation of the stone. Outstanding picture stones can be quite rare.
The photos don't really do it justice, but this is a nice example, cut and polished, ready to be set in jewelry
The multi-directional fire display would lend itself to creating a really interesting and unique pendant
(Please note the bevelled edge on the back of the stone in last pic to assist with bezel settings)
TYPE - Solid Opal Picture Stone
ORIGIN - Lightning Ridge
COLORS –Purple, Blue and Green Pinfire Sparkles on a dark grey backgound