Porphyry is a volcanic rock made by a glassy or micro-crystalline substance, which constitutes more than 65% of its whole material in which also small crystals are included. The most abundant crystals are those of quartz, and for that reason this rock is also called "quartz porphyry".

There are many varieties of colours from clear grey up to medium brown. This kind of stone is often used for outdoor applications since it is very resistant both to hard cold and to high temperatures. We can find it therefore particularly in many kinds of floorings (from the so called Sanpietrini up to medium-size slab) and it is also used for coverings, ventilated walls and plates.

For sure Porphyry was already used by the ancient Etruscans (for smelting furnace construction) and by the Romans.. Thanks to its particular characteristics, this stone was widely used both in art and in building works.