Porphyry
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 below has pinkish coloured plagioclase feldspar crystals set in a groundmass of diorite. It comes from a place called Mindoolah near the town of Cue in Western Australia.
Click here to view cut & polished specimens of porphyry
Another variety occurs in farming country near the town of Beverley not far from Perth. Someone once said that the feldspar crystals in the dolerite looked like cat foot prints. Now the name "cats paw" porphyry has stuck.
