What is Respirable Crystalline Silica?

Under the name of silica, it is identified a group of minerals composed of silicon and oxygen, the two most abundant elements in the earth’s crust. Its chemical formula is SiO2. It may be in crystalline or amorphous form, with the crystalline form being the most common in nature. The most frequent crystalline forms are quartz, tridymite and cristobalite.

Quartz is found in all types of terrestrial rocks, igneous, metamorphic and sedimentary, being the second most common mineral and main component, for example, of beach sand. There are important concentrations of quartz in granites, shales, sandstones, quartzites, clays, shales, and to a lesser extent in marbles, basalts or limestones. Cristobalite is a high temperature crystalline polymorph of silica, formed in nature as result of volcanic activity, or artificially, by the catalyzed conversion of quartz at high temperature in a rotary kiln. The quartz or cristobalite are minerals with high melting points, high hardness, translucent or transparent, and relatively inert and resistant to chemical attacks. These properties make them extremely useful and a key raw material for many industries, including the glass industry, paints, plastics and, in the case of the Cosentino® Group, in the industry of building surfaces.

The construction surfaces marketed by the Cosentino® Group have crystalline silica in these proportions by weight: Silestone® 50-90%; Dekton® 5-11%; Sensa®-Scalea® 0-99% (depending on the type of natural stone); Prexury > 90%.

Crystalline silica is safe and harmless to health. However, when materials containing crystalline silica are cut, granulated, ground, drilled, polished, or machined in similar mechanical processes, dust particles containing crystalline silica may be airborne and remain suspended in the air. Only the fraction of these particles of crystalline silica dust with a particle size smaller than 10 micrometers is capable of penetrating through the respiratory tract to the alveolar zone of the lungs. This small particle size fraction is known as the Respirable Crystalline Silica (RCS) fraction.