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Like other quarried stones, porphyry has its own unique characteristics which makes it distinctive. Historical use of the material has been noted as far back as approximately 3,000 years, when Egyptians and Romans considered it to be good luck. At that time, the word “porfirogenito” - meaning “born in a room cladded with porphyry” - was created. The same good luck that was hoped for at birth was also wished for Emperors at their death, and so they were buried in tombs made of porphyry. Nowadays, porphyry is being used for exterior and some interior applications, and companies such as Odorizzi Porfidi of Albiano, Italy, are quarrying and processing the material to markets around the world, including the U.S.
“It is a very unique material,” said Carlo Odorizzi, the company’s export manager. “It is naturally layered, and the layers give porphyry its characteristics.” The material also has a high compressive strength.
Odorizzi’s family has been in the porphyry business for nearly 50 years, and the history of porphyry quarrying is entrenched in the history of the region. In fact, Albiano is known as the “Cittá di Porfido” (City of Porphyry). Today, Odorizzi Porfidi has grown to include 300 employees worldwide.
He explained that at the end of the 19th century, the material started to be used for industrial purposes such as paving, therefore, lessening its symbolic value. “Starting after World War I, porphyry was used for paving streets and public spaces in Italy and throughout Europe because of its hardness,” said Odorizzi. “It also was a reasonable cost.”
Odorizzi went on to say that while the early porphyry deposits were in Egypt, being exploited, the Trentino area of Italy and Argentina are primarily where the quarries are found today. “It was by chance that my father discovered a big deposit in Argentina,” he said. “It was almost unknown.”
Today, Odorizzi Porfidi owns a total of 10 quarries - seven in Argentina and three in the Trentino region. Between all of its locations, the company produces 50,000 metric tons of porphyry annually.
“Each individual site has its own color,” said Odorizzi. “We have one that produces gray/brown, one that is red/gold and ones with gray, mixed red and mauve. Porphyry is 250 million years old. It came up with a volcanic eruption. The cooling process was very quick and caused the characteristics and layers. Over the years, moisture brings iron into the stone. The iron content in the stone gives it its variation in color.”
The quarrying processTo extract the porphyry, Odorizzi Porfidi begins by blasting the mountain. “We drill holes and use dynamite,” said Odorizzi. “How much we use depends on how much raw material we want to get.” He explained that the company works off levels that are 30 meters from each other.
“Blasting depends on two main aspects - the quality of the material (expressed as percentage of finished products over the raw material used to obtain them); and how many workers are in the quarry,” he said. “In our bigger quarry with 30 workers, we blast once a week.”
Stone World had the opportunity to visit one of the company’s smaller quarries in Trentino. “This one has less workers and better material,” said Odorizzi. “We blast about once a month.” He said that the quarry is about 40 years old, and the company hopes it will be fruitful for at least another 30 years. Material extracted and worked from the site is used for smaller finished products, such as cubes, flagstone and irregular wall cladding.
Odorizzi explained that long ago special artisans and craftsmen extracted and worked the porphyry by hand. “Still today, much of the work is done by hand in comparison to marble and granite,” he said.
The artistry and experience of the stoneworkers is still an integral part of the process. Skilled workers split the blocks of stone by hand, relying on their eye to choose the ideal spot to strike the stone. These splitters produce stone pieces of varying sizes.
Marketing the materialApproximately 55% of Odorizzi Porfidi’s products are sold in Italy, while Japan is also a large market for the company. The U.S. comprises approximately 5 to 10% of its market.
“We believe a lot in exporting,” said Odorizzi. “Even when it is more difficult, it is worth the investment.”
To better serve its American customers, the Odorizzi family created Porphyry USA Inc. “We believe strongly in the U.S. market,” said Odorizzi. “That is why we opened the U.S. office in 1997. Among many important projects supplied so far, the most famous is the interior stone paving of the New de Young Museum in San Francisco, designed by architects Herzog & De Mouron.”
In the U.S., brown-colored porphyry is among the more popular shades - especially in California and New England, Odorizzi explained. He added that the red/gold shade of the material is also a favorite.
“Until 2005, we mostly sold loose pieces that had to be individually set,” he said. “In 2006, we introduced a new patented technology called Hera®, which is based on mesh-mounted interlocking porphyry patterns that completely resolves any installation difficulties - allowing less-experienced installers to achieve results similar to those of experienced Italian masters, in competitive time and costs.
“The uniqueness of porphyry is that we have the natural finish, and the second is its variable thickness,” Odorizzi went on to say. “The natural cleft surface is a great anti-slip protection.”