what is quartz sand used for

what is quartz sand | how many types of quartz sand | m&c

what is quartz sand | how many types of quartz sand | m&c

Quartz sand is a kind of quartz particle formed by crushing quartzite. Quartzite, also known as siliceous rock, is a hard silicate mineral with stable chemical properties, In nature, quartzite exists in the form of quartz sandstone, quartz shale and vein quartz.

Quartz sandstone is a consolidated clastic rock with quartz clastic content over 95%, which comes from various magmatic rocks, sedimentary rocks and metamorphic rocks, less heavy minerals, and associated minerals are feldspar, mica and clay minerals; Quartzite shale is divided into sedimentary rocks and metamorphic rocks; Vein quartz is formed by hydrothermal process, almost all of which is composed of quartz.

Table of Contents What is Quartz SandHow Many Types of Quartz Sand1. Ordinary Quartz Sand2. Refined Quartz Sand3. High Purity Quartz Sand4. Fused Quartz Sand5. Silica FumeDifferent Types Quartz Sand Comparison

Ordinary quartz sand, that is, SiO2 90-99%, Fe2O3 0.06-0.02%, fire resistance 1750 . Ordinary quartz sand is generally a kind of water treatment filter material made of natural quartz ore, which is crushed, washed, dried and secondary screened;

Refined quartz sand SiO2 99-99.6%, Fe2O3 0.03-0.016%. It is made by complex processing of selected high-quality ore. Particle size range: 2-2500 mesh, can be produced according to the users requirements, white or crystalline appearance.

High purity quartz sand, SiO2 99.5-99.9%, Fe2O3 0.001%, made of high-quality natural quartz stone, carefully selected and finely processed. The particle size range is 0.005-0.01mm, 0.01-0.1mm, 0.1-0.5mm, 0.5-1mm.

Fused quartz sand is a kind of filling material. Firstly, it oxidizes quartz sand by capacitance method, and then it is processed and screened by mechanical equipment. Finally, it becomes fused quartz sand. The fused quartz sand has thermal stability, high purity, stable chemical properties, uniform particle distribution, and thermal expansion rate close to 0 point.

Fused silica sand is used as filler in paint, coating and other chemical industries. It is also the main raw material for epoxy resin casting, electronic sealing materials, casting materials, fire resistance, ceramics and glass industries.

The silica fume is processed from natural quartz and has large particle size range from 200 mesh to 10000 mesh. However, the fineness of silica fume is less than 0.001mm, accounting for > 80%, and the average particle size is 0.1-0.3 m, which is a kind of dust state.

Silica fume is used in concrete and refractory materials, adhesives and sealants, electronic industry, plastics and modified resins, paint coatings, rubber materials, tires and rubber products, greatly improving material performance.

quartz sand for landscaping | home guides | sf gate

quartz sand for landscaping | home guides | sf gate

Compacted garden soil may kill plants because their roots cannot spread to find moisture and nutrients. One amendment used to combat dense soils is quartz sand. Technically called silica sand, this sand type comes in various particle sizes so it incorporates seamlessly into the soil structure. Quartz sand has several uses in the yard.

Compacted garden soil may kill plants because their roots cannot spread to find moisture and nutrients. One amendment used to combat dense soils is quartz sand. Technically called silica sand, this sand type comes in various particle sizes so it incorporates seamlessly into the soil structure. Quartz sand has several uses in the yard.

Many trees that grow in warm climates prefer well-draining soils, including palm trees. One way to achieve good drainage is to mix quartz sand, garden soil and organic matter together. This soil trio allows air and water pockets to proliferate within the soil for optimum root nourishment. Although it is best to prepare your garden soil before planting a tree, you may amend the soil around an established tree, if needed.

Wet soil in desert gardens is a recipe for rotting cacti but quartz sand mixed into the soil creates the well-draining environment needed for growth and flowering, even during rainy seasons. One of the other major benefits of quartz sand is its minimal influence on soil pH. Unlike limestone sands, quartz sand does not increase the pH of the soil. As a result, you do not risk changing the soil's pH and damaging plants.

A properly landscaped yard does not have a perfectly flat surface -- there must be a slight slope, such as 1 percent, to funnel rainwater away from structures. Quartz sand helps you create this slope when you mix it into the surrounding soil. Your slope has proper drainage along the surface, as well as within the topsoil itself. Another way to use quartz sand for landscaping is using it in transitions. Trees do not commonly like plants directly beside their trunks but quartz sand, spread evenly across the area between a lawn and the tree creates a better aesthetic than bare soil.

You can also use quartz sand as a supportive soil layer for retaining walls. Especially handy for yards with terraced hillsides, retaining walls hold a specific amount of soil in place to create a flat area for planting. Not only does the wall's base need a layer of compacted sand, but the soil surrounding the wall needs to have a sand mixture to keep the planting area well-drained. If the area behind the wall does not drain well, the weight of trapped water and wet soil compromises its stability.

Writing professionally since 2010, Amy Rodriguez cultivates successful cacti, succulents, bulbs, carnivorous plants and orchids at home. With an electronics degree and more than 10 years of experience, she applies her love of gadgets to the gardening world as she continues her education through college classes and gardening activities.

12 important uses of quartz in daily life - valuable mineral - az chemistry

12 important uses of quartz in daily life - valuable mineral - az chemistry

Quartz is among the most important minerals. It also the most varied mineral as well as part of crystal. The compound of quartz consists of silicon material and oxygen into two tetrahydes that creates clear and crystal-like color. Form of quartz itself vary from solid to powder and often comes in two types of quartz.

The sand that glassmaker uses to create glass, one hundred percent contains quartz. On high temperature, quartz that is originally powder turns to be solid, durable, and has clear color. Moreover, during the heating process, glassmaker can easily shape the quartz almost into anything.

Product that uses glass has many variations. Given that quartz is the main material of glass makes it an important mineral and inorganic compound. Fortunately, quartz is abundant and recyclable, making glass using it a great factor of industry with a more long last period. Thus, it marks just how important quartz is in both chemistry and economy.

People notice that in their wristwatch, the material of the glass is always made from quartz. Quartz has pretty solid and durable material, thus making it ideal for creating the glass of watches. Furthermore, quartz in its original form is more affordable than any other gemstone such as diamond. Hence, mass production of watches using quartz is much more beneficial and worth the result as well.

Quartz has many variations of form and those forms are good material for gemstone jewelry. Variations of quartz are amethyst with beautiful violet color, herkimer diamond, ametrine with its purplish color, beautiful pink in rose quartz, citrine, blue quartz, prasiolite, crytsal rock that has the similar effect of diamond and many more.

The many variations of quartz make it a valuable material for jewelry making because they have beautiful colors and more affordable compared to carbon based compound like diamond orgold that have higher price and production cost.

Another use of quartz is as abrasive material. It says that quartz has strong durability and in its sand can get rid of obstacle if it is in much amount. Abrasive material is not always associated with bad thing. Some industries need abrasive material to get rid of hindrance without causing much change.

Quartz sand is good for sand blasting, sand sawing, scouring and grinding material with smoother result. Therefore, quartz sand (that belongs to normal tempered sand) is different from ordinary sand because its hard texture, despite its form, has power when user use them together as abrasive material. It proves that quartz has important use in industry.

Being one of the most durable mineral, quartz is also anti corrosive material. Chemical corrosion that often destroy a compound, be it solid or not, is common. However, quartz is sturdy enough to not get affected by chemical corrosion. In fact, quartz is among the strongest mineral with Moh scale score 7, topped only by sapphire, topaz, and diamond at the highest.

This makes quartz a reliable and durable material for household material. Aside from that, quartz is also the most abundant compared to the other three that has the strongest nature. Thus, it is relatively cheap and cut the cost for production. Products from quartz usually is more affordable than diamond or sapphire.

Among other compounds in this world, quartz can exist everywhere and pretty much very durable even to electricity. Research found quartz to be an outstanding isolator as opposite to conductor uses. Alteration of electricity that occurs within its component makes quartz does not channel electricity but blocked it instead.

Moreover, products made from quartz are more resistant to electricity than those from fabric as fabric can ignite electric reaction from friction while quartz does not. Thus, quartz is a good material for products that should not caught on electrical reaction.

Almost all sides of the world have quartz sand. It proves that quartz can endure any temperature as well as weather condition. This mineral is pretty durable to heat despite extreme temperature change compared to Heat Transfer Through Conduction Example in Daily Life. Moreover, it has solid form once it becomes industrial products. Certainly it cannot always resist heat especially when quartz sand is melted in its boiling point (in glassmaking), but once it becomes glass or when it varies as other gemstone (amethyst, ametrine, etc) it is more resistant to heat.

Compare it to polymer, paper, or wood, quartz definitely is better in resisting heat. It takes longer for heat to break the component of quartz than it on wood or polymer. Thus, it is a durable material for industrial purpose and serve important role.

Due to quartz hardness, it also works to sharpen other materials but giving continuous friction to those needs to be sharp. Sharpening tools for knives and cutleries often also has quartz in it. Strength of quartz able to overpower silver material and sharpens them instead.

The amount of quartz on the earth matches the number of benefit it has. Literally almost all industries utilize quartz along with Importance of Organic Chemistry in Industry either as main material or as supporting material. Moreover, it is more affordable than other gemstone. Owning the many uses in industry, quartz undoubtedly is one of the most important minerals in the world.

what is silica sand used for? use quartz for glass, paint, water filtration

what is silica sand used for? use quartz for glass, paint, water filtration

What is Silica Sand? Silica sand, also known as quartz sand, white sand, or industrial sand, is made up of two main elements: silica and oxygen. Specifically, silica sand is made up of silicon dioxide (SiO2). Silica sand deposits are most commonly surface-mined in open pit operations, but dredging and underground mining are also employed.

Silica sand deposits are most commonly surface-mined in open pit operations, but dredging and underground mining are also employed. Extracted ore undergoes considerable processing to increase the silica content by reducing impurities. It is then dried and sized to produce the optimum particle size distribution for the intended application.

Although quartz is often white or colourless, it can come in a wide range of shades. The colour of each sand deposit depends largely on the variety of minerals and rock detritus that make up the resource.

In order to be considered a silica sand the material must contain at least 95% SiO2 and less than 0.6% iron oxide. If the sand does not meet this criteria, it will qualify as whats often called regular sand.

Silica sand is a type of sand that mostly consists of tiny granules of quartz. Quartz itself comes in many varieties, according to its color and microstructure. Silica sand also consists of other fine particles of rock and mineral. Granules of silica sand range in diameter from 1/16 mm to 2 mm, which is approximately 2/1000 of an inch to 8/100 of an inch.

Regular sand, also known as feldspathic sand, brown sand, or construction sand, will always contain some silica, but only in amounts less than 95%. For example, typical brown sand used for concrete applications can contain up to 80% SiO2, along with varying amounts of iron, carbonate, potassium, and other trace elements/minerals.

These impurities make regular sand more chemically reactive and often darker in color when compared to silica sand. The color for non-silica sands (regular sands) can be various shades of white, pink, green, and black as well depending on the geological makeup and geographic location of the sand deposit.

Silica sand is used for many different things, such as sand blasting, glass manufacturing, water filtering, concrete and mortar mixing, landscaping and pool installation, as a spread on top of slick roads, as backfill for electrical lines and pipes, in septic tanks, as part of a loam mix, as well as many other applications.

Silica sand is a major ingredient in the production of glassmakingin fact, silica is the primary component in standard glass products ranging from windows to beer bottles. The purity of the silica sand used plays a role in determining the color, strength, and clarity of the final product. Industrial sand is used to produce flat glass for building and automotive use, container glass for foods and beverages, and tableware. In its pulverized form, ground it reinforces glass fibers and is required for the production of fiberglass insulation. Additionally, silica sand is applied in specialty glasses that include test tubes and other scientific tools, television, CRT monitors, and also in incandescent and fluorescent lamps.

Silica sand is selected to improve the appearance and durability of architectural and industrial paint and coatings. In architectural paints, silica fillers improve paints tint retention durability, and resistance to dirt, mildew, cracking, and weathering. Because of silica sands oil-absorption properties, it makes a durable coating thats rich in pigment and resistant to wear and tear.

As in other applications, silica is desirable for its chemical inertness which allows for good acid, chemical, and heat resistance. Along with its chemical inertness silicas hardness improves abrasion resistance in paints.

Industrial sand is the main structural component in a number of building and construction products. Whole grain silica is put to use in flooring compounds, mortars, specialty cement, stucco, roofing shingles, skid-resistant surfaces, and asphalt mixtures to provide packing density and flexural strength without adversely affecting the chemical properties of the binding system. As silica is resistant to weather, wear, and corrosion, it is often used as a caulk or sealant.

Ground silica is an essential component of the glaze and body formulations of all types of ceramic products, includingtableware, sanitary ware, and floor and wall tile. In the ceramicbody, silica isthe skeletal structure upon which clays and flux components attach. The SiO2 contribution is used to modify thermal expansion, regulate drying and shrinkage, andimprove structural integrity and appearance. Silica products are also used as the primary aggregate in both shape and monolithic type refractories to provide high-temperature resistance to acidic attack in industrial furnaces.

Silica sand has for a long time been used to clean as well as purify the water. 4 grades of the silica sand are majorly used for water filtration all over the world. Natural silica sand has a sub-angular to the rounded shape, which does make them ideal filtration media to be able to capture the suspended solids in the water. As a result of the high silica content, sand is durable and hard-wearing, which allows it to graded precisely so as to facilitate efficient filtering.

Industrial sand even finds its way into sports and recreation. Silica sand is used for bunkers and greens on golf courses. golf course bunkers and greens as well as the construction of natural or synthetic athletic fields. In golf and sports turf applications, silica sand is the structural component of an inert, uncontaminated growing media. Silica sand is also used to repair greens and to facilitate everyday maintenance like root aeration and fertilization. The natural grain shape and controlled particle size distribution of silica provide the required permeability and compaction properties for drainage, healthy plant growth, and stability.

Silica sand is commonly used as a mineral abrasive for industrial blasting. Though blasting with silica sand can create dangerous dust, exposure is easily avoided by following recommended PPE (personal protective equipment) guidelines and/or by coating the sand with solutions designed to control dust.

Have I missed any uses of silica sand? What other usage do you use quartz in your everyday life? Please comment below. If you want to learn more, or if youre interested in ordering silica sand, get in touch with MiningValleys today to request a quote.

Silica Sand / Quartz Sand Silica sand, also well known as Quartz Sand. It was got from the broken and ground Silica Stone / Quartz Stone. Quartz stone is a non-metallic mineral, a hard, wearable, chemical properties, and stability of silicate minerals, the main mineral composition is SiO2. Quartz sand is an important industrial mineral

Main Features High purity white Silica sand With very low Iron content, makes silica granules look ultra-pure, this grade of Silica Sand gives a very pure glass interface, with no impurities. Silica Sand 99.7% SiO2 We supply high purity silica quartz sand with Silica Dioxide +99.6% SiO2, which helps to achieve the highest quality glass

How the Sand Ceremony Performs: The bride, groom, and other family members the bride and groom wish to include each has their own color of sand. A glass vase that the couple chose beforehand should be put in the center of the table. It can be any size or shape. The only requirements are that

What is Vermiculite? Vermiculite is a kind of natural, inorganic, layered mineral that comprises a group of hydrated, laminar magnesium-aluminum-iron silicate minerals resembling mica. It is a relatively rare mineral and belongs to silicate. Vermiculite deposits are associated with volcanic ultramafic rocks rich in magnesium silicate minerals, and flakes of the mineral range in color

Silica Sand is quartz that through the work of water and wind, has been broken down into tiny granules. Also been known as white sand, industrial sand, silica sand is made of two main elements: silica and oxygen. Especially, silica sand is made up of silicon dioxide (SiO2). The color of quartz sand is milky

Cristobalite Silica Powder Cristobalite powder is made of selected vein quartz ore heated at high temperature starting at about 1500C, processed by non-polluting grinding, magnetic separation, and classification. With high purity and white color, cristobalite silica powder has stable physical and chemical properties and controllable particle size distribution is widely used as material for the

quartz sand applications in 10 different industrial fields | m&c

quartz sand applications in 10 different industrial fields | m&c

Quartz sand is an important raw material for nearly 100 kinds of industrial products, such as glass, electronics and electrical appliances, optical fiber semiconductors, water treatment, mechanical casting, artificial quartz stone, daily ceramics, metallurgy, superhard materials, chemical industry, cement, functional fillers, oil drilling and so on.

Table of Contents 1. Glass Industry2. Electronic & Electrical Industries3. High-end Quartz Material Industry4. Water Treatment Industry5. Mechanical Foundry6. Artificial Quartz Stone Plate7. Domestic Ceramics8. Metallurgical Industry9. Super Hard Material10. Chemical Industry

In the electronic and electrical industry, quartz powder (silicon powder) is an important functional filler for epoxy resin castables, filling materials, plastic sealing materials, packaging materials, engineering plastics, coatings, silicone rubber and electrode protective coatings. At present, the highest filling rate of spherical silicon powder in EMC has reached > 90%.

High-purity quartz sand is an important raw material for producing high-purity quartz tubes, quartz rods, quartz bars, quartz plates, quartz crucibles and other high-end quartz products. Optical communications, semiconductors, special materials usually require the purity of quartz sand > 99.998%, the impurities content < 22ppm, and the single alkali metals (potassium, sodium, lithium) content is less than 1ppm.

Quartz Filter: Quartz sand filter material is made of natural quartz ore as raw material and processed by crushing, washing, screening and other processes. it is the most widely used water purification material in water treatment industry

In foundry casting process, silica sand (quartz sand) is the most widely used and largest amount of foundry sand. According to the different mining and processing methods, it can be divided into natural silica sand and artificial silica sand, such as water washed sand and scrubbed sand etc.

Artificial quartz is composed of more than 90% natural quartz sand (powder) of aggregate, about 10% of pigments, resins and other additives that regulate adhesion and curing, etc. Such as vein ore quartz, sand (rock) ore quartz and weathered quartzs all can be used as raw materials for artificial quartz.

As the raw material of ceramics, quartz has non-plasticity. Quartz transformed into mullite crystals under high temperature and makes porcelain has high mechanical strength and chemical stability. Quartz can increase the translucency of the green body, so it is a good raw material for preparing white glaze.

Ceramics: The main raw materials of ceramics are high purity quartz sand, which can be used in glazes, blanks, daily ceramics, sanitary ware, household decoration tiles, floor tiles, quartz kitchen countertops, cabinets, etc.

In the metallurgical industry, quartz can be used to make refractories (silica brick), smelting siliceous alloys (ferrosilicon, silicomanganese, silicochromium) or as fluxes. Those with high silica content can be used as raw materials for industrial silicon production.

Industrial silicon carbide is divided into black silicon carbide and green silicon carbide. Black silicon carbide is made by high temperature smelting in resistance furnace with quartz sand, petroleum coke and high quality silica as the main raw materials. Green silicon carbide is made by high temperature smelting in resistance furnace with petroleum coke and high quality silica as main raw materials and salt as additive.

suitability of quartz sands for different industrial applications - sciencedirect

suitability of quartz sands for different industrial applications - sciencedirect

Quartz is found in the nature in varying purity and is traded in varying quality for different industrial applications. It can be used either for high added value applications such as silicon-metal wafers, optical glass or PV panels or for more ordinary applications such as foundry sand for metal castings or as a filler for adhesives and grouts. Extended exploration work in area of central Macedonia, resulted in the identification of medium purity quartz river deposits. Preliminary laboratory tests verified the suitability of these quartz sands to be used as filler materials for making adhesives and grouts.

relevant problems of quartz extraction technology

relevant problems of quartz extraction technology

Quartz sand (silica sand) is one of the important industrial raw materials, widely used in glass, casting, ceramics and other industries. Quartz sand is a chemically stable silicate mineral with a major mineral composition of silica.

Quartz sand (silica sand) is mainly derived from quartzite and vein quartz, which is accompanied by feldspar, mica and clay minerals, while vein quartz is accompanied by feldspar, mica, cuttings, heavy minerals, clay minerals and so on. Although the structure formed by quartzite and vein quartz is different, the composition is similar, so the selection of the mineral processing technology is similar. In the quartz sand beneficiation process, because there are fewer impurities in the raw ore, the main beneficiation process is to purify and remove a small amount of impurities in quartz sand. Currently, the processes used include: classified desliming, scrubbing, magnetic separation, flotation, acid leaching and so on.

The quartz ore has good wear-resisting. Ordinary grinding quartz sand process may not achieve a good grinding effect, as well as the grinding process consumes a lot of energy. Thus, we can improve the grinding efficiency and grinding fineness by add grinding aid dosage during the grinding process. The available grinding aids are sodium chloride, ammonium chloride, sodium oleate, triethanolamine, etc., wherein the grinding effect of adding ammonium chloride is relatively good.

It is necessary to pay attention to the amount of grinding aid dosage when using it. In a certain range, the more grinding aids you add, the finer grinding fineness you get. Once beyond this range, the increase of grinding aid dosage will cause the grinding fineness to decrease. Therefore, it is necessary to determine the amount of grinding aid dosage by testing before use.

In quartz process, the fine-grain grade with particle size below 0.1mm is usually called slime.Since the quartz containing more clay and mineral mud, with the particle size of quartz ores decreasing, the grade of silica would also be reduced while the grade of iron and aluminum would rise. Using spiral classifier to classify and deslime quartz ores is easy to operate and also can effectively reduce the impurity content. This simple method can achieve good results, but it cannot remove the thin film iron and sticky material on the surface of quartz sand.

Scrubbing refers to a process that using mechanical equipment create friction between the ore particles. The purpose of this process is to film iron, bond, and clay minerals. Scrubbing is used to remove these impurities of thin film iron and blocking impurities on the surface of quartz. Rod rubbing is an effective way to remove these impurities. The scrubbing concentration can be controlled between 50% and 60%, and the scrubbing time can be determined according to the properties, which can further reduce the impurity in quartz.

Quartz sand xenoclasts contain hematite, limonite, biotite and other weak magnetic separation minerals as well as secondary cast iron in the crushing process. Usually, strong magnetic separation equipment is used to remove these impurities. If there is magnetite impurity in quartz sand, it can be removed by weak magnetic separation equipment.

Some conclusions obtained from previous studies include:The higher the number of magnetic separations, the lower the iron content of quartz sand;The higher the magnetic field intensity is, the more iron impurities can be removed, but the iron removal rate will not increase when the magnetic field intensity is increased to a certain level;The finer the granularity of quartz sand, the better the effect of iron removal;In addition, the effect of iron removal is also related to the particle size of quartz sand. The smaller the particle size of quartz sand is, the better the effect of iron removal is.

The purpose of quartz flotation process is to remove the non-magnetic associated impurities, such as feldspar, mica. These impurities are similar to quartz in element composition and structure, which is difficult to separate from the quartz. The quartz flotation process can be divided into fluorine flotation process and fluorine-free flotation process. Fluorine flotation process means to separate the quartz with cation collector and hydrofluoric acid activator. Due to the serious impact of fluorine on the environment, the fluorine-free flotation process was developed. The fluorine-free flotation process uses the sulfuric acid or hydrochloric acid to regulate the pH value of the pulp, and adopts the anion cation collector to separate quartz and mica. In addition, using anion - cation collector flotation process in alkaline condition can also get better flotation effect.

Quartz sands have stable characteristic, for they dont dissolve in acid expect HF. So there is acid leaching method using acid to dissolve impurities in quartz. The common acid includes sulfuric acid, muriatic acid, nitric acid, and so on. Different kinds and concentrations of acid are selected for different metal impurities in quartz sand.Usually diluted acid are used to remove iron and aluminum, and concentrated sulfuric acid,aqua regia, and hydrofluoric acid are used to remove titanium and chrome.

Since the resolution aqua regia, the concentration of commonly under 10%. Acid leaching was highly influenced by acid concentration, acid dosage, time, temperature, and other factors. It needs to maintain rather low cost by controlling all the factors through quartz grade.

Common quartz sand(silica sand) extraction technology flow includes scrubbing classifying desliming, scrubbing desliming magnetic separation, scrubbing desliming magnetic separation flotation, scrubbing desliming magnetic separation flotation acid leaching and so on.

Scrubbing desliming magnetic separation flotation acid leaching is suitable for quartz minerals still with little impurities after scrubbing, magnetic separation and flotation. High grade quartz sand(silica sand) can be get from this processing flow.

quartz | definition, types, uses, & facts | britannica

quartz | definition, types, uses, & facts | britannica

Quartz, widely distributed mineral of many varieties that consists primarily of silica, or silicon dioxide (SiO2). Minor impurities such as lithium, sodium, potassium, and titanium may be present. Quartz has attracted attention from the earliest times; water-clear crystals were known to the ancient Greeks as krystalloshence the name crystal, or more commonly rock crystal, applied to this variety. The name quartz is an old German word of uncertain origin first used by Georgius Agricola in 1530.

Quartz has great economic importance. Many varieties are gemstones, including amethyst, citrine, smoky quartz, and rose quartz. Sandstone, composed mainly of quartz, is an important building stone. Large amounts of quartz sand (also known as silica sand) are used in the manufacture of glass and ceramics and for foundry molds in metal casting. Crushed quartz is used as an abrasive in sandpaper, silica sand is employed in sandblasting, and sandstone is still used whole to make whetstones, millstones, and grindstones. Silica glass (also called fused quartz) is used in optics to transmit ultraviolet light. Tubing and various vessels of fused quartz have important laboratory applications, and quartz fibres are employed in extremely sensitive weighing devices.

Quartz is the second most abundant mineral in Earths crust after feldspar. It occurs in nearly all acid igneous, metamorphic, and sedimentary rocks. It is an essential mineral in such silica-rich felsic rocks as granites, granodiorites, and rhyolites. It is highly resistant to weathering and tends to concentrate in sandstones and other detrital rocks. Secondary quartz serves as a cement in sedimentary rocks of this kind, forming overgrowths on detrital grains. Microcrystalline varieties of silica known as chert, flint, agate, and jasper consist of a fine network of quartz. Metamorphism of quartz-bearing igneous and sedimentary rocks typically increases the amount of quartz and its grain size.

Quartz exists in two forms: (1) alpha-, or low, quartz, which is stable up to 573 C (1,063 F), and (2) beta-, or high, quartz, stable above 573 C. The two are closely related, with only small movements of their constituent atoms during the alpha-beta transition. The structure of beta-quartz is hexagonal, with either a left- or right-handed symmetry group equally populated in crystals. The structure of alpha-quartz is trigonal, again with either a right- or left-handed symmetry group. At the transition temperature the tetrahedral framework of beta-quartz twists, resulting in the symmetry of alpha-quartz; atoms move from special space group positions to more general positions. At temperatures above 867 C (1,593 F), beta-quartz changes into tridymite, but the transformation is very slow because bond breaking takes place to form a more open structure. At very high pressures alpha-quartz transforms into coesite and, at still higher pressures, stishovite. Such phases have been observed in impact craters.

Quartz is piezoelectric: a crystal develops positive and negative charges on alternate prism edges when it is subjected to pressure or tension. The charges are proportional to the change in pressure. Because of its piezoelectric property, a quartz plate can be used as a pressure gauge, as in depth-sounding apparatus.

Just as compression and tension produce opposite charges, the converse effect is that alternating opposite charges will cause alternating expansion and contraction. A section cut from a quartz crystal with definite orientation and dimensions has a natural frequency of this expansion and contraction (i.e., vibration) that is very high, measured in millions of vibrations per second. Properly cut plates of quartz are used for frequency control in radios, televisions, and other electronic communications equipment and for crystal-controlled clocks and watches.

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