The Royal Stone

By Kate Parrott

For thousands of years, porphyry has been renowned as a beautiful and durable paving and facing stone. A type of volcanic rock consisting of large-grained crystals such as feldspar or quartz, which is formed by a slow cooling process of igneous materials, the stone is valued for its aesthetically pleasing appearance. The term "porphyry" itself refers to the purplish red hues of the stone; in Latin, porphyry means purple.

While porphyry has become a popular paver today, it was originally used for sarcophaguses, busts, vases and columns. The stone that was extracted in the Egyptian desert in the mountain Jebel Dhokan is known as Imperial Red porphyry or Ancient Red porphyry.

Aside from its beauty and durability, porphyry has been revered as a status symbol through the ages. Roman emperors were surrounded by the stone, born in rooms made of the porphyry and were sometimes even buried in sarcophaguses made of the stone. Today, it is highly regarded for both its functionality and beauty.

Quarries
With quarries found the world over, until recently, the stone was most commonly quarried in Italy, notably in Trentino. There, porphyry is characterized by felsic phenocrystals within a mass of red or pinkish gray color.

Legal issues related to the extraction of porphyry in Italy, along with the desire for a higher level of processed material, such as sawed, polished, semi-polished and flamed, have led to more recent quarrying outside of Europe. Quarry operators also have shown recent interest in the quarrying of porphyry blocks.

Mexican and Iranian porphyry typically display a deep red color, while Argentine porphyry includes diverse varieties, ranging from red to mauve to gray. In some areas of Argentina, the porphyry is quite compact, allowing for the extraction of regular blocks.

In Peru, an unusual type of porphyry, called Verde Esperanza, is quarried. This stone is characterized by a green color, which suggests the presence of chlorite. Verde Esperanza is mostly used as slabs, with the surface polished or flamed.

Colors
While the Latin name porphyry translates as "purple," its title can be quite deceptive. Porphyry is commonly known for its striking red and purple colors, but the stone can be found in shades of green, gray, gold, brown and black as well.

Red porphyry is often interspersed with small white spots, caused by feldspar and shorl deposits. Higher quantities of feldspar yield more transparent stones. When jasper enters its composition, porphyry is more opaque and highly colored.

Applications
Porphyry is highly prized for its durability as a paver, making it an ideal stone for walkways, driveways, courtyards, driveways and facades. Because it is freeze/thaw- and slip-resistant, porphyry is ideal for any type of outdoor flooring application.

Various sizes, shapes and thicknesses of porphyry are available, including cubes, binders, irregular slabs, ashlar stones, natural tiles and machined tiles. Porphyry cubes, or cobblestones, have perhaps been the most popular throughout the ages and are one of the most popular applications today.

Binders are a versatile product and are often used to mark the edge of paved areas, such as with flowerbeds and traffic islands. Binders also can be used to face low walls and steps. Irregular slabs, distinguished by their sizes and thicknesses, are generally used for paving external areas, such as squares and gardens.

Irregular slabs have a natural surface and rough-cut edges. Ashlar stones are typically used for facing supporting walls or as coverings for building facades. The front face can be sawn or shaped naturally. Natural tiles are used for paving and facing of both internal and external areas. They are ideal for squares, streets, sidewalks and historical centers. Finally, machined tiles present a stylish and refined finish and are most appropriate for elegant interior areas.

Porphyry is available in a number of finishes, including unpolished, polished, semi-polished, honed, flamed, sand blasted, bush hammered and antiqued.

Interesting Facts
Porphyry has long been prized for its beauty and perception as a stone of royalty. In ancient times, Egyptians were one of the first people to successfully quarry the stone, and Egyptian kings and queens were the exclusive benefactors of porphyry works and masterpieces.

In 300 A.D., the ancient Romans utilized the stone to decorate royal palace rooms for family members of the royal empire. Romans also used porphyry to build their roads. The highly durable stone can still be seen throughout Rome today, although in some places it is crumbling. However, the crumbling is not to any fault of the stone. After the fall of Rome, people scavenged for the prized stone, which was highly regarded for its strength and beauty, to use for their homes and town squares.

In the late 16th to early 17th centuries, it is said that King Louis XIV of France once had the world's largest collection of porphyry stone.