Polished Porphyry . PO 122 oldest agate in the world Dimensions at widest points approximately

Dimensions at widest points approximately 105 mm  x 95 mm wide x 6 mm thick

Dimensions at widest points approximately 225 mm x 80 mm x 14 mm thick

Dimensions at widest points approximately 110 mm  x 100 mm wide x 6

IRR 132    Fossil stromatolite slab

170 mm x 100 mm x 9 mm

Polished Porphyry . PO 122 oldest agate in the world Dimensions at widest points approximatelyPO122. Pink porphyry slab, cut and polished on one side. From Mindoolah, Western Australia. Dimensions at widest points approximately 290 mm x 165 mm x 10 mm thick. Weighs 898 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