Polished Porphyry . PO 123 Green Opal 70 million years (Cretaceous)

70 million years (Cretaceous)

Very rare fossil stromatolite slab polished on one side

From south west of Newman Western Australia

Weighs 146 grams

Polished Porphyry . PO 123 Green Opal 70 million years (Cretaceous)PO123. Pink porphyry slab, cut and polished on one side. From Mindoolah, Western Australia. Dimensions at widest points approximately 140 mm x 80 mm x 8. 5 mm thick. Weighs 188 grams. Porphyry is a general term that is used rather loosely for igneous rocks which contain relatively large isolated crystals set in a fine grained groundmass. The porphyry pictured here has pinkish coloured clinozoisite crystals set in a ground mass of dolerite. The