Feldspar

Half the Earth's crust

Feldspar is the name given to a group of naturally occurring alumino-silicate minerals containing varying amounts of potassium, sodium, calcium, and/or lithium. The feldspar group of minerals is by far the most abundant group of minerals in the Earth’s crust, making up about 50% of all rocks. Feldspar minerals are essential components in igneous, metamorphic, and sedimentary rocks, to such an extent that the classification of a number of rocks is based on their feldspar content.

Although highly present in igneous rocks like granite, commercial feldspar is generally mined from pegmatite or feldspathic sand deposits.

Feldspars are generally divided into three categories, feldspar, pegmatite and feldspathic sand, and are primarily used in industrial applications for their alumina and alkali content. Feldspars and pegmatites play an important role as fluxing agents in ceramics and glass production, and are valuable functional fillers in the paint and adhesive industries.

Physical properties

• High alumina and alkali content
• High potassium content
• Low iron content
• Chemical inertness
• pH stable
• Consistent hardness (6-6.5 on Mohs scale)

A wide portfolio of minerals with specific properties

Imerys operates feldspar mines and processing plants in France, Germany, Portugal (plants), Spain (plants), Turkey, United States, India and Thailand. 

Each operation yields feldspars of different mineral and chemical compositions which we engineer to impart specific properties to a wide range of end products such as ceramics, glass and paints.

Glass and ceramics lead the way 

In glassmaking, Imerys feldspars are excellent fluxing agents for flat and container glass, as well as for insulation wools. Feldspar is an excellent source of alumina which improves end product hardness, durability, and resistance to chemical corrosion.

Used in ceramics, feldspar and pegmatite are the main vitrifying or fluxing agents used during the firing process of ceramic bodies. Fluxes melt at an early stage in the firing process forming a glassy matrix that bonds the other components of the system together, ensuring the durability of fired bodies. Imerys feldspars contain low levels of coloured oxides, so they are particularly prized for white tiles and sanitaryware production.

Fine-milled Imerys feldspars are valuable multi-functional fillers and extenders in applications such as paints for their good dispersibility, chemical inertness, stable pH, high resistance to abrasion, and low viscosity.

Imerys has a wide portfolio of feldspar and pegmatite products. With in-depth knowledge of how feldspar interacts in our customers’ end products, we will continue to harness our minerals to help customers improve performance, reduce costs and minimize their carbon footprint.

Image