While building science continues to introduce new methods and materials to improve the quality, integrity, and sustainability of the built environment, legacy materials continue to maintain their favored status.

Natural stone, for example, is a non-renewable product from an extractive industry, yet it provides a stable, safe, and reusable building material that can last for generations.

Integrating natural stone into modern applications is commonplace, yet fraught with challenges, according to Werner Nierhoff of RMS Natural Stone and Ceramics. Natural stone is classified in the quarry for different uses, typically by those with decades of experience.

Given that most are usually not well trained to recognize faults, cracks, and other problems with the material, a substantial challenge is developing a good eye for the product, which requires years of experience, Nierhoff said. Quarrymen develop their skills over time, then recruit their offspring.

“In most cases it goes from one generation to the next and even a third, due to the exposure from a very young age of the children of quarry owners and processing facility owners,” Nierhoff noted.

Quarrymen must distinguish between features and faults, and must be able to make judgments about the stone’s suitability for different applications.

“What some people regard as faults may not be faults. It may simply be the nature of the stone,” Nierhoff said, adding that without experience, “it would be nearly impossible to be able to judge the quality and suitability of stone if it’s simply a block of stone, or sitting in the quarry.”

Beyond appearance, natural stone must be evaluated for its suitability for certain uses. Density and absorbency are key factors. Structural applications require high-density stone, while wet applications require a stone with low absorbency. These factors are established via extensive testing in university laboratories and institutions such as CSIRO, Nierhoff said.

Lesser-quality stone, however, is also useful and can be used for a variety of projects, depending on how stable it is.

“It can be a very good, solid, strong stone. However, it doesn’t have any appeal in terms of tonality, veining, and the like,” Nierhoff noted. “Such stone can be used either in commercial projects, or it will be used for other purposes such as mosaics.”

Outdoor pavers also are suitable for stone that is not top quality. Such stones often receive a surface treatment, such as sandblasting. These treatments can considerably change the appearance of the surface and can make a stone that lacks attractive veining or other features be useful for outdoor paving and similar circumstances.

For consumers looking to buy natural stone, the risk of paying too much for inferior stone is high, Nierhoff said.

“Stone is not easily classed between premium and commercial quality, so it’s often sold at a premium price when it was acquired as seconds,” he said. “Most consumers will never be aware of it. However, it is a very opportunistic approach by some distributors.”

Another challenge for consumers is the lack of barriers for unqualified merchants, according to Nierhoff.

“Because trading in stone doesn’t require qualifications, everybody can start tomorrow selling stone who doesn’t have a license or any other qualifications to do so,” he said.

Consumers can, however, educate themselves about the what makes for high-quality stone. It’s helpful to check with industry associations, such as CSIRO and the Australian Stone Advisory Association (ASAA). In addition, look to established suppliers who have been in business for decades and have a solid reputation. Check their products, and inquire about their reputation and qualifications.

Getting good value for the product is important, certainly, but probably not the most important factor.

“In the end, of course, the last and probably decisive factor is the usually the appearance or the likes or dislikes of the final customer,” Nierhoff said.