Porphyry is now quarried in many countries including Italy (near Trentino as shown at right), Argentina and Mexico. Porphyry is prized for its great compressive strength and exceptional durability. For this reason it is now most commonly used as a paving stone.

Where can I find porphyry?

Rhomb porphyry is found in continental rift areas, including the East African Rift (including Mount Kilimanjaro), Mount Erebus near the Ross Sea in Antarctica, the Oslo graben in Norway, and south-central British Columbia.

How are porphyry formed?

The porphyry deposits are formed by differentiation and cooling of a column of rising magma in stages. The different stages of cooling create porphyritic textures in intrusive as well as in subvolcanic rocks.