Quartz vs. Fused Silica: What are the Differences?

This article will explore the unique properties of fused silica and quartz, as well as a few related materials to clear up the confusion surrounding these terms.

Quartz vs. Silica
One of the most important things to know regarding fused silica and quartz is that they both primarily consist of silica, also known as silicon dioxide. Silica is the primary constituent of most types of glass and has the chemical formula SiO2.

Mineral quartz is the main form in which silica is found in nature; mineral quartz makes up an appreciable fraction of the Earth’s crust and is a hard, transparent crystalline material. Besides silica, quartz also contains naturally occurring impurities in various proportions that are dependent on its geological origin.

‘Silica’ refers to a specific chemical compound, silicon dioxide, with the chemical formula SiO2. Meanwhile, quartz is a naturally occurring crystalline mineral that primarily consists of silica but contains some impurities.

Crystalline and Amorphous Solids
In order to understand the differences between different silica-based materials, there first needs to be an understanding of the fundamental differences between amorphous solids and crystalline solids.

The way that the atoms are arranged inside the solids is how to define the difference. The constituent atoms are arranged in regular, repeating patterns known as crystal lattices in a crystalline solid. One example of a crystalline silica-based material is quartz: oxygen and silicon atoms are arranged in a well-defined ordered structure.

The atoms in an amorphous solid, however, have no long-range order. In an amorphous solid, the seemingly random arrangement of molecules resembles those of a liquid, except that they do not move around and are instead fixed in place.

Amorphous solids make up most materials that we think of as “glass”. Indeed, the term “glassy” can be used to describe any material with an amorphous atomic structure.

A material’s characteristics can be profoundly influenced based on whether its atoms are oriented randomly or are arranged in an orderly manner. The glass transition effect exhibited by amorphous solids is one of the most striking examples of this.

Beyond the realm of silica or other oxide-based materials, disordered “glassy” metals are often chosen for use because of their unusual mechanical characteristics when compared to other conventional metals.

Quartz and other silica-based materials can be characterized both in terms of whether they are amorphous or crystalline, as well as by their chemical composition.

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