Sodium Feldspar
Feldspar is a group of related aluminosilicate minerals
WHAT IS
Sodium Feldspar?
Feldspar is not a single mineral but a family of closely related aluminosilicates that make up more than half of the Earth’s crust. The three primary types—sodium feldspar (albite), potassium feldspar (orthoclase) and calcium feldspar (anorthite)—differ in their alkali composition but share similar crystal structures and properties.
Covia’s sodium feldspar, marketed under the MAXUM® brand, is valued for its high purity, whiteness and balanced chemistry—rich in silica, alumina and sodium oxide with minor potassium. This combination provides both structural strength and fluxing ability, making it an essential ingredient in the manufacture of ceramic and glass products.
For glass manufacturing, Covia’s feldspathic sand deposit in Emmett, Idaho, offers a naturally balanced combination of silica and feldspar—approximately 87% silica with 8% alumina and trace amounts of sodium and potassium. The Emmett operation supplies feldspathic silica sand under the brand GLASSIL® FS for fiberglass and flat and container glass applications.
With a high alumina content that enhances durability and brightness, and alkalis that lower melting temperatures, sodium feldspar supports efficient firing and improved product performance in industrial applications.
PHYSICAL AND CHEMICAL PROPERTIES
Sodium feldspar is primarily composed of silica (SiO₂), alumina (Al₂O₃) and sodium oxide (Na₂O), with minor potassium and iron oxides.
WHERE DOES SODIUM FELDSPAR
Come From?
Covia operates two sodium feldspar facilities in Mexico and a feldspathic sand operation in the United States:
- Ahuazotepec, Puebla – Covia’s primary feldspar mine, known for its high-purity deposits and award-winning operations.
- Benito Juárez, Nuevo León – A processing facility that refines feldspar ore from Ahuazotepec to meet diverse customer specifications.
- Emmett, Idaho – This facility produces high-quality feldspathic sand, a naturally blended material of silica and feldspar that supports glass, fiberglass and construction material production.
Planning /
Geology
At Covia’s Ahuazotepec mine, feldspar is extracted from natural deposits and transported for processing. The ore is crushed, milled and screened to achieve the desired particle size distributions. Magnetic separators remove trace iron contaminants, enhancing brightness and purity.
In addition to its sodium feldspar operations in Mexico, Covia also operates a feldspathic sand facility in Emmett, Idaho. This long-life surface mine extracts high-quality sand, which is processed, graded and screened before shipping.
Covia’s quality assurance processes ensure every shipment meets strict chemical and physical specifications.
Mythbusters
Sustainability
Message
Covia’s feldspar operations in Mexico exemplify responsible mining, community partnership and environmental stewardship.
Our Ahuazotepec, Puebla facility has earned Covia’s Plant of the Year Award for two consecutive years, recognizing excellence in safety, manufacturing, environmental management and community engagement.
Through its Community Action Plan, the Ahuazotepec site has forged partnerships with the Zacatlán Municipal Government, the State Government of Puebla, the National Forestry Commission and the Drinking Water Operating System to advance biodiversity and conservation efforts.
Highlights of this ongoing collaboration include:
- The donation of 30,000 trees to local communities and participation in 60 reforestation events to restore native habitats and protect water resources.
- An exceptional safety record with zero lost-time or recordable incidents and active PASST certification.
- Successful EPA inspections and air compliance with no violations, demonstrating Covia’s disciplined environmental practices.
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