Rough cut plasma agate slab.  Slabs are approximately .25 inch thick.  This slab has not been polished, just sliced.  Plenty of interesting material here for cabbing or this is a nice showy piece in rough form.  Approx. 6 inch at its widest point.  Pen marking on one side can usually be removed with rubbing alcohol if you do not plan to cut and polish the piece.