Key Roles of Quartz in Everyday Life and Industry
Quartz is one of the most abundant minerals found on Earth. Its chemical composition primarily constitutes silicon dioxide (SiO2) or silica and oxygen; however, minor impurities, including sodium, lithium, titanium, and potassium, can also be present. Its physical and chemical properties make it one of the most useful natural materials on the planet.
A widely distributed mineral on the Earth's surface, quartz is a crucial constituent of igneous, metamorphic, and sedimentary rocks. It is formed in igneous rocks as magma cools and silicon dioxide crystallises.
Quartz is highly resistant to chemical and mechanical weathering and can form at all temperatures. This is why mountaintops and beaches, sea, and desert sand are abundant with quartz.
In this article, we will learn quartz types and meanings and know where quartz come from.
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Importance and Uses of Quartz
The demand for quartz is quite high due to its economic importance and quartz use in a huge variety of sectors. Here are some of them.
Quartz is highly durable and chemically inert with most substances, in addition to its heat resistance and other electrical properties, which makes it a valuable mineral in electronic products.
Its lustre, colour, and diaphaneity make it useful as a gemstone and in making glass.
Different types of quartz are used in different industries, including as gemstones, like rose quartz, smoky quartz, amethyst, and citrine.
Quartz is a major component of Sandstone, essentially used as a building stone.
Silica sand or Quartz sand is used in the glassmaking industry to manufacture ceramics, glass and moulds for metal casting. It is used to make container glass, flat plate glass, speciality glass, and fibreglass.
Crushed quartz is an excellent abrasive used in sandpaper, sandblasting, and grit for sanding and sawing.
Silica glass (also known as fused quartz) is employed in optics to transmit ultraviolet light.
The ability of quartz crystals to vibrate at precise frequencies makes the mineral useful in extremely accurate time-keeping instruments where radio and television signals are required to be transmitted at specific and stable frequencies.
Quartz fibres also find their use in extremely sensitive weighing devices.
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Quartz Occurrence
Quartz is an important mineral in silica-rich felsic rocks such as granodiorites, rhyolites, and granites, which is present in high concentrations in sandstones and other detrital rocks. Microcrystalline varieties of silica, such as flint, chert, jasper, and agate, also consist of an exemplary quartz network.
The world's major and primary quartz-producing countries include Japan, Russia, and China. Additionally, Brazil, Belgium, France, Bulgaria, South Africa, the United Kingdom, and Germany also mine significant amounts of this mineral.
Existence of Quartz
Quartz minerals exist in two forms. Let us discuss the types of quartz or quartz types and their meanings.
Alpha or the low quartz - It is stable at 573 °C (1,063 °F).
Beta or high quartz is stable above the temperature of 573 °C.
The two types of quartz only differ in the alpha-beta transition, which occurs due to small movements of their constituent atoms. The alpha-quartz structure is trigonal with a right-handed symmetry group, while the beta-quartz structure is hexagonal, with either left- or right-handed symmetry groups equally populated in crystals.
At the transition temperature, the beta-quartz's tetrahedral shape twists, which results in the symmetry of alpha-quartz. However, the beta-quartz changes into tridymite at temperatures more than 867 °C (1,593 °F). At very high pressure, the alpha-quartz transforms into the coesite and still, at higher pressures, as stishovite.
Quartz: A Piezoelectric
Quartz is a naturally occurring piezoelectric crystal. A piezoelectric crystal is one that develops both positive and negative charges on an alternate prism edge when subjected to higher stretching or pressure. These charges are proportional to the change in pressure. Since a quartz crystal has silicon atoms with a positive charge and oxygen atoms with a negative charge, when it is stretched or pressed, the arrangement of the atoms changes slightly, giving it a piezoelectric property.
Thus, a quartz plate is used as a pressure gauge, as a depth-sounding apparatus. Also, due to its properly cut plates, quartz can be used for frequency control in televisions, radios, and other electronic communications equipment, and crystal-controlled watches and clocks.
Synthetic and Artificial Treatment
It is important to remember that not all quartz varieties are naturally occurring. Some clear quartz crystals are also treated using gamma or heat irradiation to induce the colour where it would not otherwise occur naturally; this treatment depends on the location where the quartz is mined.
Prasiolite, which is an olive-coloured material, can be produced by heat treatment; natural prasiolite has also been observed in the Lower Silesia in Poland. Although the citrine takes place naturally, the majority is given as the result of smoky or heat-treating amethyst quartz. To deepen its colour, carnelian is widely heat-treated.
So, after reading this article, you will have gained a better understanding of the quartz meaning, quartz mineral uses, types of quartz and its occurrence.
FAQs on Quartz: Properties, Structure, and Importance in Chemistry
1. What is quartz and what is its chemical composition?
Quartz is a hard, crystalline mineral that is one of the most abundant minerals in the Earth's crust. Chemically, it is composed of silicon dioxide, with the chemical formula SiO₂. It consists of a continuous framework of silicon-oxygen tetrahedra, where each oxygen atom is shared between two tetrahedra.
2. What are the key physical and chemical properties of quartz?
Quartz has several distinct properties that make it valuable:
- Hardness: It has a hardness of 7 on the Mohs scale, making it very durable and resistant to scratching.
- Crystal System: It belongs to the trigonal crystal system.
- Lustre: It typically has a vitreous (glassy) lustre.
- Chemical Inertness: Quartz is chemically stable and does not react with most acids, except for hydrofluoric acid.
- Piezoelectricity: It generates an electric charge when mechanical pressure is applied, a property known as the piezoelectric effect.
- Melting Point: It has a very high melting point of around 1670 °C (for β-quartz).
3. How are silicon and oxygen atoms arranged in the crystal structure of quartz?
The structure of quartz is a giant covalent structure or network covalent solid. The basic structural unit is the SiO₄ tetrahedron, where a central silicon atom is covalently bonded to four oxygen atoms. Each of these oxygen atoms is then shared with an adjacent tetrahedron. This creates a strong, stable, and continuous 3D framework, which explains its high hardness and melting point.
4. What are the main uses of quartz in various industries?
Due to its unique properties, quartz is used in many applications:
- Electronics: Its piezoelectric property is crucial for making crystal oscillators used in watches, clocks, radios, and computers.
- Glassmaking: High-purity quartz sand (silica sand) is the primary ingredient for making glass.
- Jewellery: Varieties like amethyst, citrine, and rose quartz are used as semi-precious gemstones.
- Construction: It is a major component of construction materials like concrete and mortar. Engineered quartz is also popular for countertops.
- Abrasives: Its hardness makes it an effective abrasive for sandblasting and grinding.
5. Why is the piezoelectric property of quartz so important in modern electronics?
The piezoelectric property is the ability of quartz to generate a small, precise voltage when it is squeezed or bent. Conversely, when a voltage is applied to a quartz crystal, it vibrates at a very precise frequency. This property is vital for frequency control in electronic devices. A tiny, accurately cut quartz crystal acts as a highly stable resonator in crystal oscillators, which are essential for keeping accurate time in watches and for stabilising frequencies in computers, mobile phones, and radio transmitters.
6. What is the difference between alpha-quartz (α-quartz) and beta-quartz (β-quartz)?
Alpha-quartz and beta-quartz are two different polymorphs (crystalline forms) of SiO₂. The main difference is the temperature at which they are stable.
- Alpha-quartz (α-quartz): This is the low-temperature form, stable up to 573 °C. It has a trigonal crystal structure. Most quartz found at the Earth's surface is alpha-quartz.
- Beta-quartz (β-quartz): This is the high-temperature form, stable from 573 °C up to 870 °C. It has a hexagonal crystal structure.
7. How does the structure of quartz differ from that of quartz glass (fused silica)?
The key difference lies in their atomic arrangement.
- Quartz: It is a crystalline solid. This means its SiO₄ tetrahedra are arranged in a highly ordered, repeating, long-range pattern. This regular structure is responsible for its distinct crystal shape and sharp melting point.
- Quartz Glass (Fused Silica): It is an amorphous solid. While it is also made of SiO₂ tetrahedra, they are arranged randomly with no long-range order, similar to the structure of a liquid. This is why glass does not have a sharp melting point but softens over a range of temperatures.
8. What are some common colourful varieties of quartz used as gemstones?
Pure quartz is colourless and transparent. However, trace amounts of impurities can give it a wide range of colours, leading to many popular gemstone varieties:
- Amethyst: Purple, coloured by iron impurities.
- Citrine: Yellow to orange-brown, also coloured by iron.
- Rose Quartz: Pink, coloured by trace amounts of titanium, iron, or manganese.
- Smoky Quartz: Brown to black, caused by natural irradiation of aluminium impurities.
- Milky Quartz: White and translucent, due to microscopic fluid inclusions.
