Albiano Quarry
Albiano Quarry, Italy

Porphyry is a volcanic rock which belongs to the so called “Atesina porphyry platform”. It takes its name from the area of Albiano, in Italy.

Albiano is the home, in every sense, of this natural stone. The porphyry stone is the result of a long and intense volcanic activity, that began 260 millions of years ago and which pursued for several millions of years by alternating eruptive and standstill phases.

Porphyry is quarried from an ignimbrite classified as “rhyolitic ignimbrite” and the workable thickness is about 100-200 meters, because of the lack of stratification.

Porphyry is the only natural stone with a quarry natural surface. Its the chemical composition (over 70% silica, about 14% alumina, 8% alkali and small percentages of iron, calcium and magnesium), the mineral composition (quartz, sanidine and plagioclase crystals with a smaller quantity of biotite and of pyroxenes in a vitreous paste) and the marked porphyry features that determinate the technical characteristics of this natural stone.

The high compression breaking point, the high resistance to chemical agents and the high sliding and rolling friction make of porphyry a very versatile and noble material which can be used thanks to its physical and mechanical characteristics and to its wide range of colours for the most diverse applications, actually, it’s a material that always guarantees excellent results even in the case of rather difficult and original projects.

Cembra Valley
Porphyry mine, Cembra Valley, Italy

The stone sits vertically within the mountain, similar to slate, and the thickness is determined by the natural formation of the stone. Only some materials can be as thick as 40 cm. Porphyry is not an industrialized product it is decided by nature, and it passes through many hands before it becomes the final product.

To extract the stone, black powder explosives are used at the base of a stone wall ranging from 15 to 40 meters in height. After the material is freed and falls to the quarry floor, it is separated with Caterpillar loaders. The first worker to handle the stone has the difficult and important task of splitting the stone to the maximum thicknesses given by nature. This is critical and the most important difference in quality, because if not done properly, freeze/thaw cycles can split the stone after it has been set. From there, workers use hand tools or splitting machines to bring the stone pieces to their final dimensions, and it is loaded directly onto a palette. The waste level in the quarry runs between 40 and 60%.