Quartz Mineral Britannica

Mineral

Mineral - Crystal Habit, Aggregation: The external shape (habit) of well-developed crystals can be visually studied and classified according to the various crystal systems that span the 32 crystal classes. The majority of crystal occurrences, however, are not part of well-formed single crystals but are found as crystals grown together in aggregates. Examples of some …

Agate | Varieties, Uses, Formation | Britannica

Agate, common semiprecious silica mineral, a variety of chalcedony that occurs in bands of varying colour and transparency. Agate is essentially quartz, and its physical properties are in general those of that mineral. See silica mineral (table). Agate is …

quartz

Mineral

Mineral - Oxides, Hydroxides, Compounds: These classes consist of oxygen-bearing minerals; the oxides combine oxygen with one or more metals, while the hydroxides are characterized by hydroxyl (OH)– groups. The oxides …

Greisen | Mineralogy, Granite, Pegmatite | Britannica

greisen, modification of granite, an intrusive igneous rock; it consists essentially of quartz and white mica (muscovite) and is characterized by the absence of feldspar and biotite. The rock usually has a silvery, glittering appearance from the abundance of layered muscovite crystals, but many greisens resemble a pale granite. The white mica mostly forms large plates with …

Mineral

Mineral - Hardness, Mohs Scale, Crystalline: Hardness (H) is the resistance of a mineral to scratching. It is a property by which minerals may be described relative to a standard scale of 10 minerals known as the Mohs scale of hardness. The degree of hardness is determined by observing the comparative ease or difficulty with which one mineral is scratched by another …

Mineral

Mineral - Polymorphism, Crystalline Structure, Chemical Compounds: Polymorphism is the ability of a specific chemical composition to crystallize in more than one form. This generally occurs as a response to …

Igneous rock

Igneous rock - Minerals, Magma, Crystals: The major mineralogical components of igneous rocks can be divided into two groups: felsic (from feldspar and silica) and mafic (from magnesium and ferrous iron). The felsic minerals include quartz, tridymite, cristobalite, feldspars (plagioclase and alkali feldspar), feldspathoids (nepheline and leucite), muscovite, and corundum.

Quartz | Properties, Varieties, Occurrence and Uses …

Quartz is a mineral that is composed of silicon and oxygen atoms in a continuous framework of SiO4 silicon–oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical formula of SiO2.

Mineral synthesis | Britannica

In silica mineral: Quartz …to the development of industrial synthesis methods based on the differences in silica solubility with temperature. Nutrient crystals are placed in the hot portion of a solution-filled autoclave, and an oriented seed crystal …

Plasma | Ionized Gases, Electron Density & Magnetic Fields | Britannica

plasma, in mineralogy, semitranslucent, microgranular or microfibrous, semiprecious variety of the silica mineral chalcedony.Its colour, various shades of green, is due to disseminated silicate particles of different kinds—e.g., amphibole or chlorite. Other properties are those of quartz.Plasma often has nodules of gray quartz or red jasper (bloodstone) throughout its mass.

Venus's-hairstone | mineral | Britannica

Venus's-hairstone, variety of quartz interspersed with fine crystals of the mineral rutile

Mineral

Mineral - Nesosilicates, Structure, Chemistry: The silicon-oxygen tetrahedrons of the nesosilicates are not polymerized; they are linked to one another only by ionic bonds of the interstitial cations. As a result of the isolation of the tetrahedral groups, the crystal habits of these minerals are typically equidimensional so that prominent cleavage directions are not present. …

Sagenite | mineral | Britannica

Other articles where sagenite is discussed: rutile: …rutile in quartz are called sagenite (from the Greek word for "net"). Hairlike crystals of rutile not included in quartz are rare; the quartz crystals mechanically enclose the rutile during growth. Most fine-quality rutilated quartz comes from Minas Gerais, Brazil; Madagascar; Hanover, New Hampshire; and northern Vermont.

Quartz | Definition, Types, Uses, & Facts | Britannica

Quartz is the second most abundant mineral in Earth's 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.

Quartz | Earth Sciences Museum | University of …

Quartz is our most common mineral. Quartz is made of the two most abundant chemical elements on Earth: oxygen and silicon. Atoms of oxygen and silicon join together as tetrahedrons (three sided pyramids).

Coesite | Metamorphic, Quartz & High-Pressure | Britannica

coesite, a high-pressure polymorph (crystal form) of silica, silicon dioxide (SiO 2).It has the same chemical composition as the minerals cristobalite, stishovite, quartz, and tridymite but possesses a different crystal structure.Because of the very high pressure necessary for its formation, it does not occur naturally in the Earth's crust. . Artificially produced in 1953 by the American ...

Chert and flint | Mineral, Sedimentary Rock | Britannica

chert and flint, very fine-grained quartz (q.v.), a silica mineral with minor impurities.Several varieties are included under the general term chert: jasper, chalcedony, agate (qq.v.), flint, porcelanite, and novaculite. Flint is gray to black and nearly opaque (translucent brown in thin splinters) because of included carbonaceous matter. Opaque, dull, whitish to pale-brown or …

Authigenic mineral | geology | Britannica

Other articles where authigenic mineral is discussed: sedimentary rock: Mineralogical and geochemical composition: …two principal types—namely, detrital and authigenic. Detrital minerals, such as grains of quartz and feldspar, survive weathering and are transported to the depositional site as clasts. Authigenic minerals, like calcite, halite, and gypsum, form in situ …

Lazulite | Manganese, Phosphate & Magnesium | Britannica

Lazulite, phosphate mineral, a basic magnesium and aluminum phosphate [MgAl2 (PO4)2(OH)2], that often occurs as blue, glassy crystals, grains, or masses in granite pegmatites, aluminous metamorphic rocks and quartzites, and quartz veins. It is found in Werfen, Austria; Västarå, Sweden; Mocalno,

Kyanite | Metamorphic, Aluminium Silicate, Mohs Scale | Britannica

kyanite, silicate mineral that is formed during the regional metamorphism of clay-rich sediments. It is an indicator of deep burial of a terrain.Kyanite occurs as elongated blades principally in gneisses and schists, and it is often accompanied by garnet, quartz, and mica.It can also occur in igneous rocks such as granite.Its colour ranges from gray-green to black or blue, with blue and …

Amethyst | Purple Quartz, Healing Properties, …

Amethyst, a transparent, coarse-grained variety of the silica mineral quartz that is valued as a semiprecious gem for its violet colour. Its physical properties are those of quartz, but it contains more iron oxide (Fe2O3) than any other variety …

Smoky quartz | Healing, Metaphysical & Grounding | Britannica

smoky quartz, very common coarse-grained variety of the silica mineral quartz that ranges in colour from nearly black through smoky brown. No distinct boundary exists between smoky and colourless quartz. Its abundance causes it to be worth considerably less than either amethyst or citrine. Heating bleaches the stone, the colour sometimes passing through yellow; these yellow …

High quartz | mineral | Britannica

High quartz, or β-quartz, is the more symmetrical form quartz takes at sufficiently high temperatures (about 573 °C at one atmosphere of pressure), but the relationship is pressure-sensitive. High quartz may be either left- or right …

mineral

Encyclopædia Britannica, Inc. ... One of the most common minerals, quartz occurs in many areas in a variety of forms. Semiprecious gem stones of quartz include amethyst, tigereye, agate, and onyx. Siliceous sinter, or geyserite, is an impure quartz deposited by hot springs and is a form of opal. The fire opal has an internal iridescence of ...

Quartz

As a mineral name, quartz refers to a specific chemical compound (silicon dioxide, or silica, SiO 2), having a specific crystalline form (hexagonal). It is found in all forms of rock: igneous, metamorphic and sedimentary. Quartz is …

quartz summary | Britannica

quartz, Second most abundant mineral (after feldspar) in the Earth's crust, present in many rocks. Quartz, which consists of silica, or silicon dioxide (SiO 2), 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 ...

Collection – All Sorts of Quartz | Smithsonian …

Quartz is the major component of beach sand and an important mineral in many types of rocks, including granite. Quartz is composed of the elements silicon and oxygen, and in its pure state is colorless. However, just small amounts of …

Mohs hardness | Definition, Table, Examples, & Facts | Britannica

Mohs hardness, rough measure of the resistance of a smooth surface to scratching or abrasion, expressed in terms of a scale devised (1812) by the German mineralogist Friedrich Mohs. The Mohs hardness of a mineral is determined by observing whether its surface is scratched by a substance of known or defined hardness.. To give numerical values to this …

quartz

The two most common chemical elements in the Earth's crust, oxygen and silicon, combine to form the mineral quartz, the second most abundant mineral after feldspar. Quartz has the chemical formula SiO 2. Sometimes minor impurities—such as lithium, sodium, potassium, and titanium—may be present. There are many varieties of quartz.