This porphyritic rock currently used by the building construction industry for floorings, traditional and ventilated-wall facings, is a type of effusive volcanic rock - rhyolitic and rhyodacitic ignimbrites - that is commonly found in the earth's mantle. Some of the thicker and more renowned formations of closely fractured ignimbrites are to be found in Italy, Argentina, and Mexico. Less thick, fractured formations are found in Australia, Japan, and Greece.
Non-fractured ignimbrites, i.e. without slab formation, also exist in Italy, Argentina, Germany, Peru, Poland, Turkey, Spain, Iran, China, and Mexico. Petrographically speaking, porphyry consists of a microcrystalline to vitreous groundmass, which makes up over 65% of its volume, containing up to 30-35% of small crystals (sizes 2-4 mm). The most abundant crystals consist of quartz, which explains why this rock is also known by the name of "quartz porphyry." Porphyry also contains a small percentage of feldspar and traces of mica minerals.
Porphyry's technical characteristics make it one of the most important materials for paving and facing in europe, America and around the world. Porphyry is stronger than granite with more than 31,000 psi. The increase in the concern for safety and durability has led to the adoption of protective surfaces, which are slip resistant, prevent slipping, impermeable, easy to repair, have minimal installation and maintenance cost, offer an economic solution because of its durability; and yes, porphyry resists staining on floors and walls from your coffee or drink at the Hard Rock Cafe or Starbucks coffee shop. You can live with and enjoy the stone for a long-long time. The services to maintain are minimum. Use a good stone neutral cleaner from Fila, Aquamix, StoneTech, Miracle Sealants or other major professional stone care company. And for stronger cleaning or maintenance jobs use a product from Proseco.
I love this stone and so will you. Call Porphyry USA or Milestone Imports for supply or other information related to this stone. Both are in the USA with supplies in New Jersey, Florida, California, and New Mexico.
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Originaly published in Stone Industry News
We love stone. We love Limestone. From Indiana to Germany; limestone comes to the built environment. There are many opportunities in residential and commercial restoration of stone if you are willing and able to take a grind to the stone, and get into the heart of stone. This article is dedicated to our memories of our colleagues Michael Wiston of Valley Marble and Maurizio Bertoli of MB Stone Restoration both of whom I had the honor to know. So have many of you. There are mechanisms of stone decay upon limestone and calcareous stones by oxides of nitrogen and sulfur. These are chemical mechanisms. There is also moisture, and the most common sources of moisture that cause damage to stone. In this case we picture a limestone facade and small sample area of an architectural element affected by moisture. This particular house is in East Hampton, New York where salt air and moisture problems can be mitigated with maintenance, repair, and restoration. Cleaning, restoration, and maintenance can help avoid such conditions on limestone buildings as cracks, spalling or staining, or scaling. Limestone close to H=3 when well lithified (uniformly cemented) can be deceivingly soft. And then you have the Empire State Building and the others "Hard as a Rock" as they say. Structural cracks, gaps at joints between components and large openings are the evident problems in many cases as this one is pictured here. An investigation of load bearing elements such as columns, and beams, will establish whether those components are performing as they were originally designed, or the stress patterns have been redistributed. A common method of restoration and maintenance on stone in such conditions is filling cavities, cracks, and smoothing or refinishing stone surfaces; otherwise known as grinding, honing, and polishing. We all have listened to the expression "Marble Polishing" and so there is "Limestone Polishing" Smoothing the surface and opening and then closing the pores is a key to proper maintenance.
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Ed Hartz joined other members of the Marble Institute of America (MIA) on a tour of several marble quarries in New England. Geologic forces push calcium carbonate deposits such as limestone deep below the surface of the Earth, where heat and pressure form Marble crystals. A similar geological process forms granite from silica deposits. Later geologic forces lifted the marble and granite to the surface where it is economical to quarry the stone for architectural and artistic uses. The conditions that form each marble deposit are slightly different: the ratio of calcium carbonate to magnesium carbonate varies, the presence and amounts of other minerals varies, the pressure and temperature to form marble crystals varies, and the sequence of events that cause inclusions and veining varies. The conditions that form each granite deposit also vary; the duration of temperature and pressure as the silica deposits rise and cool determine how large the quartz crystals will become. The percentage of other minerals such as feldspar and aluminum and the fractures that allow inclusions create the patterns that make granite such an interesting material. The MIA members visited the quarries to see first hand the subtle differences throughout each quarry and the differences between the quarries.
The tour set out in a gray rain in Barre, VT, for the Rock of Ages Visitors Center in Graniteville, where company Vice President Bob Campo showed Ed the monument and mausoleum manufacturing process up close. Rough granite slabs of the desired color and pattern are cut to the required shape, polished, engraved and sand blasted to produce the individual monuments. Following the tour of the manufacturing facility, Ed visited the E. L. Smith Quarry, also owned by Rock of Ages. Granite has been quarried here since 1880. One familiar monument constructed with this granite is the World War II Memorial that opened in 2003. Ed saw diverse granite monuments at the Hope Cemetery in Barre.
A visit to the Vermont Granite Museum of Barre supplied more history and details about the quarrying and manufacturing of architectural granite. At the next stop, Granite Importers owner, Jake Colgan, accompanied Ed an the rest of the MIA group as they walked through the fabrication facility, which was in the process of working on giving a polished finish to curved pieces of Cambrian Black granite for the Mandarin hotel in Boston. Black shows every flaw and curved surfaces are difficult to polish so Ed was very interested to see the techniques that produce the highest quality finish.
The marble part of the tour included the Danby marble quarry, operated by Vermont Quarries Corp. of Rutland, VT. Luca Mannolini, General Manager, led a tour of their facility and the Imperial quarry, in Dorset Mountain, which is the largest underground marble quarry in the U.S. Danby marble was used to construct the U. S. Supreme Court Building, Jefferson Monument and several other prominent buildings, but 90% of the marble has been used for kitchen countertops. Ed examined the facility that produces 30,000 square feet of marble per month, and took photographs of the giant blocks before they are cut into slabs.
Ed and the MIA tour visited the Marble Museum in Proctor, VT, a unique resource of the extent and variety of marble from throughout the world. Philip Gawet of Gawet Marble and Granite recounted the history of the marble industry in Vermont, which is illustrated in the photographs in the museum. The museum is housed in a former factory and warehouse and includes the adjacent abandoned quarry. The worked face of the upper portion of the quarry is dramatically reflected in the rainwater that has collected in the pit. Another highlight of Proctor is a recently restored marble bridge that you will cross on the way to the museum.
The final stop on the tour was the Bethel White quarry, owned by Rock of Ages. Bob Campo explained that the stone quarried there is some of the whitest granite in the world, and a premium quality material. One characteristic of this stone is that it can be cut in either direction and still look the same.
The tour provided the depth and detail of information about New England marble and granite that is only possible with direct face-to-face discussions. Ed and the rest of the MIA group are extremely grateful to their hosts for sharing their knowledge and expertise.
The entrance to the marble mine
At the top of an open pit marble quarry
Descending the marble quarry—notice the tiny people
The working level of the marble quarry
Ed Hartz at the working level of the marble quarry
Approaching the Marble Museum
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One of the strong selling points of natural stone is longevity. Natural stones endure through years of use, even centuries of harsh weather. Natural stone has been the obvious choice for monuments and prominent public buildings. Natural stone is a complement to landmark buildings; great design deserves to be preserved in durable stone.
What do we do with our monuments and significant architecture after a hundred years or even just a few years of use, when the original bright finish is dull and various stains have accumulated? We could sacrifice the history and artistry of the original by replacing it with something new, or we could celebrate its endurance by restoring the original appearance of the natural stone.
Restored natural stone encourages the use of more stone in new places. The restored marble floor in the foyer of a pre-war home, reassures the new homeowner that remodeling the master bathroom with marble will be an investment, not just a beautiful way to spend money. Restoring a significant public building or monument reminds consumers that natural stone repays the additional cost.
Natural stone has been promoting green building practices since the first caveman built the second stone wall with materials from the first stone wall. Natural stone is, well, natural. It is recyclable, reusable and renewable. In many places, restoring and reusing natural stone building materials will generate credits that will get the building permit approved or even allow a larger addition.
Restoration supports preservation. Preservation sells the unmatched durability of natural stone. Preservation maintains our connections with history. Preservation conserves our finite earth resources. Everyone benefits.
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Ed Hartz continually reads books, magazines and Internet articles to keep current with topics in the stone industry. We have included references to a few of the best on a variety of topics: some that will interest the general reader and some that will interest the professional.
The photography and the quality of the printing are reason enough to read this publication of The Stone Foundation. The magazine specializes in presenting excellent photographs of ancient and enduring stone structures, some in ruins and some maintained for continual use. Of course, the accompanying stories are written from the point of view of stone industry professionals, and there are intelligent discussions of the type of stone and the methods of construction. The photographs and articles will take the reader around the world from Europe to Asia, Africa and the Americas.
In addition to artistic and literary content, the professional will find interesting descriptions of techniques used by leading professionals in different aspects of the stone industry. Professionals describe recent projects and include discussions of the key decisions they made.
The Stone Foundation publishes Stonexus, www.stonefoundation.org.
Stone Industry News
This tabloid-sized newspaper is essential for keeping track of the people and businesses in the stone industry. Stone Industry News prints the business announcements of the stone industry: job promotions, business acquisitions, new products and the like. It also prints interesting business discussions, including ethics, promotion and successful strategies. Even the non-professional will enjoy the articles on recently completed stone projects.
Stone Industry News is independent of any stone association or trade group. It is published monthly by Industry News, Inc, www.stoneindustrynews.com.
Slippery Rock Gazette
The Slippery Rock Gazette is a tabloid like the magazine in the Sunday newspaper. In addition to industry announcements, a variety of industry professionals contribute regular columns on topics ranging from business strategies, and “how-to” instruction to random topics on life in general. The advertising includes most major manufacturers operating in the US.
Find Slippery Rock Gazette at www. Slipperyrockgazette.net.
Written by Alfonso Acocella
Pub Date: December 2006
Category: Architecture - Methods & Materials
US Price: $150.00
CAN Price: $200.00
ISBN: 978-88-7624-696-8 (88-7624-696-7)
Trim Size: 9-1/2 x 13
About this Book
In this sweeping volume, Professor Acocella analyzes every type of stone, from those used by the Egyptians to the marble used by Mies van der Rohe. Stone as a material is not only analyzed from a historical point of view, it is categorized and examined according to its technological usage. The book is based on comparison and confrontation between origins, archetypes and present-day themes, examining a variety of projects from around the world. It provides an in-depth analysis of the enormous potential of building in stone. A combination of dense, carefully construed chapters are designed to summarize the essence of the material in its various architectonic roles through a series of specially created technical drawings, and a range of original drawings and photos.
About the Author
Alfonso Acocella is professor of technology of architecture at the University of Ferrara, Italy. His previous books include studies of contemporary architecture in Italy.
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