11. The open-pit mining of porphyry copper deposits was adopted worldwide. 12. In the batholiths there are quartz-feldspar porphyry and dolerite dykes. 13. Mineralization occurs within the Laramide intrusive and in the surrounding Precambrian porphyry . 14. The entire island constitutes the Porphyry Island Provincial Park or nature reserve. 15. The quarry also features a very thick intrusion of porphyry . 16. The fa�ade is covered with marble, strips of porphyry and verd antique. 17. Most are ground from grayish green, banded slate, and occasionally porphyry . 18. Porphyry may also have been present at this meeting.19. It is believed that tectonic change acts as a trigger for porphyry formation. 20. The intrusive quartz-porphyries are equally well described as granite-porphyries.
