Although closely associated with plutonic igneous rocks, porphyry mineralization commonly encompasses large volumes of the surrounding host rocks to the intrusion.
A porphyry obscures the contact between the Cross Slieve Group and the Red Arch Formation.
They also noted that much kaolin is in or near decomposed porphyry bodies that overlie the largest ore shoots in the Leadville Dolomite.
The Main Channel conglomerate is made up of a variety of well-rounded felsite, granophyre, and quartz-feldspar porphyry pebbles, suggesting a geologically diverse source terrane.
Some of the finest cuprite specimens ever found have come from the oxidized zones of several of Arizona's porphyry copper and related deposits.
The ore is associated with plagiogranite porphyry of Mesozoic age.
The mine workings occupy much of the west side of an isolated low hill composed mainly of light-colored volcanic rock, described as felsite porphyry or trachyte, highly altered to clay minerals.
This is particularly well known to collectors familiar with porphyry copper deposits of Arizona, New Mexico, and Utah.
This rare work of porphyry , limestone, serpentine and onyx is unique north of the Alps.
Final polishing will only succeed on the hardest of stones, such as granite, porphyry , and gemstones, and again abrasive materials will be used for this, including abrasive powders or salts.