Cristobalite
As a mineral polymorph of silica, cristobalite is silicon dioxide.
WHAT IS
Cristobalite?
Because cristobalite begins as silica sand, it has the same chemical composition as quartz, but in this case there is a unique crystalline structure. Cristobalite is formed by heating silica sand with flux material in a high-temperature kiln that reaches a temperature in excess of 2,500 degrees F. This process changes the morphology of the grain, including its color and appearance. Cristobalite maintains the natural strength and hardness of silica while providing benefits associated with its change in color and composition. Cristobalite does exist naturally in some volcanic rock but is not economic to mine in this natural state.
Cristobalite is typically an ultra-white material used as an important pigment and extender in applications such as paints and coatings, roof coatings, roofing granules, plastics, grouts and mortars. Because of its natural properties, it is also a preferred material used in ultra-white engineered quartz countertops and other surfaces. Cristobalite is often used as an extender in place of TiO2.
PHYSICAL AND CHEMICAL PROPERTIES
Cristobalite is a vitreous, translucent solid that often appears white because of the reflected light.
WHERE DOES CRISTOBALITE
Come From?
North America has vast deposits of silica sand, with significant sources found in regions like the Intermountain West, Midwest, the Great Lakes area, and the southern parts of the United States. Our geology and mine planning teams play a vital role in procuring and developing quality mineral deposits so Covia and our customers have access to consistent, reliable products for their high-value applications now and into the future.
Covia currently has 27 silica sand mining plants in North America which are strategically located within geological formations that contain extensive deposits of high-quality silica sand such as Ordovician St. Peter Sandstone, Devonian Oriskany Sand, Tertiary-Miocene Pinehurst Sand, Cambrian Jordan Sandstone, Cambrian Galesville Formation, Ordovician Oil Creek Sandstone, Cambrian Cairnside (Potsdam) Sandstone, Eocene (Tertiary) Carrizo Sandstone and many others.
With such a diverse portfolio of deposits spanning from Canada to Mexico, our silica sand can exhibit variations in its color, grain size, roundness, sorting, purity, and other physical properties. For example, the sand chemistry, defined as the composition, structure, and trace minerals, depends on the geologic formation. The formation also impacts the trace elements, including iron oxide, aluminum oxide, calcium oxide, titanium oxide, magnesium oxide, potassium oxide, and sodium oxide. Covia is recognized for our outstanding, proprietary processing methods which can substantially remove detrimental trace minerals from our products, based on our internal quality management standards.
Planning /
Geology
Let’s start at the beginning when the silica sand is still in the ground. Covia has 50 years’ mining experience that leaves the earth in better condition than when we first encountered the mineral deposit. We mine the sand from an extremely pure deposit, and our processing removes the few contaminants. What remains are low-iron grains that require less resin for bonding. In the next phase, we apply a proprietary process using a high-temperature kiln to produce our cristobalite, known for achieving consistent, brighter whiteness in the end-products.
Applications /
Markets
Fascinating
Facts
The white spots in this volcanic rock are cristobalite; in this state, the in-situ mineral is not economic to mine. Covia uses a proprietary process to produce a signature-quality cristobalite from silica sand to support customers across North America.
Sustainability
Message
Our solutions-oriented innovation supports customers where they are in their specific ESG journey. At times, we collaborate with a customer to improve product quality or, for example, divert waste from landfill. Sometimes, our collaboration centers on fulfilling an unmet need in the marketplace or reducing a customer’s carbon footprint by right-sizing and localizing specialized capacities. Covia's cristobalite is produced in the United States, providing our customers a domestic alternative to material that is transported internationally, thus reducing their carbon footprint.
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