Silica (Frac Sand) & Silicon Dioxide

When people think of the mineral wealth of the Wisconsin, most of the focus is trained towards the iron and lead bearing ores of the state. For over a hundred years though, sand, chemically known as silicon dioxide (SiO₂), has been used for a variety of applications. Sand has been used key ingredient in mortar for masonry work and concrete. It has been used to create molds for foundries that create iron products. Sand has been used as filtration devices for swimming pools, drinking water filters, and wastewater treatment plants. The glass industry also has used sand from Wisconsin in the past in its manufacturing process.

Within the past 40 years, sand from Wisconsin has found a new use to society. But not just any old sand. Sand formed in the Cambrian and Ordovician ages (approximately 540 to 440 million years ago) is used by the oil and gas industry to extract previously unrecoverable deposits of these resources. What is special about these deposits of sand is that the sand is almost purely quartz. Quartz grains are particularly strong and can withstand the intense pressures used in the "fracing" process. The grains are very well rounded, instead of being hexagonal like other quartz crystals. The last feature of this sand is the grains are just the right size to work with the equipment drillers use in the "fracing" process..

Figure 1 - Picture of quartz grains of frac sand

Courtesy of UW Extension

The demand for this special type of sand called "frac sand" has increased dramatically since 2000. Due to Wisconsin's topography and geology, many layers of bedrock containing frac sand are easily accessible for miners. Frac sand deposits are at the surface or exposed on hillsides in the much of western half of the state. Through out western and central Wisconsin mining and processing operations have sprung up in many locations to take advantage of the resource.

With this boom in frac sand mining occurring, environmental concern about frac sand mining have arose. Residents near these operations have become concerned that dust stirred up by the mining and processing of the sand creates silica dust. Residents with property close to the mines and processing plants complain of fine silica dust being blown from the mines onto neighboring properties and houses. The concern with silica dust is if it is inhaled repeatedly has been linked to silicosis, a lung disease characterized by shortness of breath and lesions forming in the lungs.