Why is quartz used in glass?

We use glass in a lot of different ways in our lives. We drink out of it, look through it, and sometimes even cook with it. But what is this material that we take for granted?

To an outsider, looking in, glass seems like a pretty simple material. But there’s actually a lot going on behind the scenes. The main component in glass is quartz.

You might be familiar with quartz as a countertop material, but it’s actually one of the most abundant minerals on Earth.

Before we get into why quartz is used in glass, let’s take a step back and shortly explore what glass is.

What is Glass?

Glass is a non-crystalline, typically transparent amorphous solid with widespread practical, technological, and decorative uses.

At a basic level, glass is made from sand. But not just any sand, it has to be super-fine and has very few impurities. The sand is then mixed with other materials like sodium carbonate and calcium oxide.

Glass Manufacturing

The mixture is heated up to around 2,700 degrees Fahrenheit until it melts and becomes a liquid. Once it cools down, the result is glass.

The term “glass” is used in a variety of ways. It can refer to the actual material, which is an amorphous solid, or to objects made from this material. It can also be used as a generic term for all types of transparent, amorphous solids, including those made from other materials.

The physical properties of glass are determined by the way it is produced. The most common method for making glass is the float glass process, in which molten glass is poured onto a pool of molten tin.

The glass spreads out over the surface of the tin and forms a flat sheet. This method produces what is known as float glass, which is characterized by its smooth, glossy surface.

What is Glass made of?

Glass is composed of silica (SiO2), soda (Na2O), and lime (CaO), with minor quantities of other oxides. The exact composition of a particular glass depends on the intended use of the glass.

silica sand
Silica sand or quartz sand

For example, leaded glass contains small quantities of lead oxide (PbO), which increases its density and refractive index.

Similarly, borosilicate glasses contain boron oxide (B2O3) to increase their resistance to heat. The addition of these oxides alters the properties of the glass, such as its density, refractive index, and melting point.

Why is Quartz Used in Glassmaking?

One of the most important ingredients in glassmaking is silica, which is derived from quartz.

Quartz is a very abundant mineral found all over the world. In fact, it’s the second most abundant mineral on Earth, after feldspar.

There are many good reasons to use quartz in glassmaking. Here are just a few:

Hardness

Quartz is one of the hardest minerals on Earth. It is measured at a 7 on the Mohs scale of hardness, which means it can only be scratched by minerals that are harder than it.

This makes quartz an excellent choice for glassmaking, as it gives the glass a high level of durability.

High Melting Point

Quartz has a very high melting point, which is why it’s used in glassmaking. Quartz can withstand temperatures of up to 1,700 degrees Celsius (3,092 degrees Fahrenheit).

This means that it can be used in the production of high-strength glass, such as bulletproof glass.

High thermal shock resistance

Another reason quartz is used in glassmaking is because it has a high thermal shock resistance. This means that it can withstand sudden changes in temperature without shattering.

This is an important property of glass, as it means that the glass can be used in a variety of applications, such as cookware and scientific equipment.

That said, no material is perfect, and depending on the degree of thermal shock glass may experience, it can still break.

Depending on the intended use of the glass, glass needs to be reinforced with other materials to make it stronger. For example, Pyrex is a type of glass that is made with borosilicate. This gives the glass a high resistance to heat and thermal shock, making it ideal for use in cookware.

Low Thermal Expansion

When heated, most materials expand. This is due to the increased energy of the atoms in the material as they are heated.

The amount by which a material expands when heated is known as the material’s coefficient of thermal expansion.

Quartz has a very low coefficient of thermal expansion, which means that it expands very little when heated.

This means that it doesn’t expand or contract much when exposed to changes in temperature. This is an important property for glass, as it helps to prevent the glass from cracking or shattering.

High Refractive Index

The refractive index is a measure of how much light is bent when it passes through a material.

Quartz has a high refractive index, which means it bends light to a greater degree than other materials. This makes quartz an ideal choice for making lenses and other optical components.

Resist abrasion well

A lot of applications need the material to be wear-resistant. From car windshields to phone screens, there are many things that need to resist abrasion.

Quartz is very resistant to abrasion, which means it doesn’t scratch or wears down easily, especially under high-stress conditions.

This makes it ideal for use in applications where the glass will be subject to a lot of wear and tear under high-stress conditions.

Can be improved to meet the purpose

Glass has a wide range of properties that can be tailored to meet the needs of the specific application. For example, by adding different oxides to the glass, the properties of the glass can be changed.

The properties of quartz can be improved by adding other materials, such as lead oxide (PbO), boron oxide (B2O3), or aluminum oxide (Al2O3).

These additions alter the refractive index, density, and melting point of quartz, which gives the glassmaker more control over the final product

Chemically Inert

Chemical inertness is the ability of a material to resist chemical reactions with other materials.

Quartz is chemically inert, which means it doesn’t react with other materials. This makes it ideal for use in food and beverage containers, as well as in laboratory equipment.

Electrically Insulating

Quartz is a poor conductor of electricity, which means it doesn’t allow electricity to flow through it easily. This makes it ideal for use in electrical applications where glass is used as an insulator.

For example, light bulbs use glass not only to protect the filament from the air but also to prevent electrical current from flowing through the glass.

If the glass were a good conductor of electricity, the current would flow through the glass and endanger the user.

Can be recycled

Quartz can be recycled and reused indefinitely. This makes it a very sustainable choice for glassmaking. It also helps to reduce the environmental impact of glass production.

It’s abundant

As Quartz is the second most abundant mineral on Earth, it’s relatively easy to find and extract. It isn’t rare or precious, so it doesn’t add to the cost of glass production. This makes it a very cost-effective choice for glassmaking.

Conclusion

There are many other minerals that can be used to make glass, but quartz is one of the most popular choices because of its many advantageous properties.

It’s abundant, chemically inert, and has a very high melting point, making it an ideal choice to use in glassmaking.

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