Hornblende

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Hornblende

Hornblende is a complex inosilicate

Silicate minerals

The silicate minerals make up the largest and most important class of rock-forming minerals, comprising approximately 90 percent of the crust of the Earth....
series of mineral

Mineral

A mineral is a naturally occurring solid formed through Geology processes that has a characteristic chemical composition, a highly ordered atomic structure, and specific physical properties....
s. Hornblende is not a recognized mineral in its own right, but the name is used as a general or field term, to refer to a dark amphibole

Amphibole

Amphibole defines an important group of generally dark-colored rock-forming Silicate minerals minerals, composed of double chain SiO4 tetrahedron, linked at the vertices and generally containing ions of iron and/or magnesium in their structures....
. It is an isomorphous mixture of three molecule

Molecule

In chemistry, a molecule is defined as a sufficiently stable, electric charge neutral group of at least two atoms in a definite arrangement held together by very strong chemical bonds....
s; a calcium

Calcium

Calcium is the chemical element with the symbol Ca and atomic number 20. It has an atomic mass of 40.078 amu. Calcium is a soft grey alkaline earth metal, and is the fifth most abundant element by mass in the earth's Crust ....
-iron

Iron

Iron is a chemical element with the symbol Fe and atomic number 26. Iron is a Group 8 element and period 4 element. Iron is lustrous and silvery in color....
-magnesium

Magnesium

Magnesium is a chemical element with the symbol Mg, atomic number 12, atomic weight 24.3050 and common oxidation number +2.Magnesium, an alkaline earth metal, is the ninth most abundance of the chemical elements in the universe by mass....
silicate, an aluminium

Aluminium

Aluminium or aluminum is a silvery white and ductile member of the boron group of chemical elements. It has the symbol Al; its atomic number is 13....
-iron-magnesium silicate, and an iron-magnesium silicate. Manganese

Manganese

Manganese is a chemical element, designated by the symbol Mn. It has the atomic number 25. It is found as a Oxidation state in nature , and in many minerals....
, titanium

Titanium

Titanium is a chemical element with the symbol Ti and atomic number 22. Sometimes called the ?space age metal?, it has a low density and is a strong, lustrous, corrosion-resistant transition metal with a silver colour....
, and sodium

Sodium

Sodium is an element which has the symbol Na , atomic number 11, atomic mass 23 amu , and a common oxidation number +1. Sodium is a soft, silvery white, highly reactive element and is a member of the alkali metals within "group 1" ....
are sometimes present. Fluorine

Fluorine

Fluorine is the chemical element with the symbol F and atomic number 9. Fluorine forms a single bond with itself in elemental form, resulting in the diatomic F2 molecule....
often substitutes for the hydroxyl

Hydroxyl

Hydroxyl in chemistry stands for a molecule consisting of an oxygen atom and a hydrogen atom connected by a covalent bond. The neutral form is a hydroxyl Radical and the hydroxyl anion is called a hydroxide....
in the structure. The general formula can be given as (Ca,Na)_2–3(Mg,Fe,Al)₅(Al,Si)₈O₂₂(OH,F)₂.

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Encyclopedia

Hornblende is a complex inosilicate

Silicate minerals

The silicate minerals make up the largest and most important class of rock-forming minerals, comprising approximately 90 percent of the crust of the Earth....
series of mineral

Mineral

Amphibole

Molecule

Calcium

Iron

Iron is a chemical element with the symbol Fe and atomic number 26. Iron is a Group 8 element and period 4 element. Iron is lustrous and silvery in color....
-magnesium

Magnesium

Aluminium

Manganese

Manganese is a chemical element, designated by the symbol Mn. It has the atomic number 25. It is found as a Oxidation state in nature , and in many minerals....
, titanium

Titanium

Sodium

Fluorine

Hydroxyl

Mohs scale of mineral hardness

Not to be confused with Siemens_#Mho, a unit of electric conductance.The Mohs scale of mineral hardness characterizes the scratch resistance of various minerals through the ability of a harder material to scratch a softer material....
of 5–6, a specific gravity

Specific gravity

Specific gravity is defined as the ratio of the density of a given solid or liquid substance to the density of water at a specific temperature and pressure, typically at 4?C and , making it a dimensionless quantity ....
of 2.9–3.4 and is typically an opaque green, greenish-brown, brown or black color. Its cleavage

Cleavage (crystal)

Cleavage, in mineralogy, is the tendency of crystalline materials to split along definite Crystallography structural planes. These planes of relative weakness are a result of the regular locations of atoms and ions in the crystal, which create smooth repeating surfaces that are visible both in the microscope and to the naked eye....
angles are at 56 and 124 degrees. It is most often confused with the minerals augite

Augite

Augite is a Silicate_minerals#Single_chain_inosilicates: mineral described chemically as SiO3 or calcium magnesium iron silicate. The crystals are monoclinic and prismatic....
and biotite

Biotite

Biotite is a common Silicate minerals#Phyllosilicates mineral within the mica group, with the approximate chemical formula K3AlSi3O102....
mica, both of which are black and can be found in granite

Granite

Granite is a common and widely occurring type of Intrusion , felsic, igneous rock rock . Granite has a medium to coarse texture, occasionally with some individual crystals larger than the groundmass forming a rock known as Porphyry ....
and in charnockite

Charnockite

Charnockite is applied to any orthopyroxene-bearing granite, composed mainly of quartz, perthite or antiperthite and orthopyroxene , as an end-member of the charnockite series ....
.

Hornblende is a common constituent of many igneous

Igneous rock

Igneous rock is one of the three main Rock types . Igneous rock is formed by magma being cooled and becoming solid . They may form with or without crystallization, either below the surface as Intrusion rocks or on the surface as extrusive rocks....
and metamorphic rocks such as granite

Granite

Syenite

Syenite is a coarse-grained intrusive igneous rock of the same general composition as granite but with the quartz either absent or present in relatively small amounts ....
, diorite

Diorite

Diorite is a grey to dark grey intermediate Intrusion igneous rock composed principally of plagioclase feldspar , biotite, hornblende, and/or pyroxene....
, gabbro

Gabbro

Gabbro refers to a large group of dark, coarse-grained, intrusive igneous rock chemically equivalent to basalt. The rocks are Intrusive, formed when molten magma is trapped beneath the Earth's surface and cools into a crystalline mass....
, basalt

Basalt

Basalt is a common extrusive volcanic rock. It is usually gray to black and fine-grained due to rapid cooling of lava at the surface of a planet....
, andesite

Andesite

Andesite is an igneous rock, volcanic rock, of Igneous rock#Chemical classification, with aphanitic to porphyritic texture. The mineral assemblage is typically dominated by plagioclase plus pyroxene and/or hornblende....
, gneiss

Gneiss

Gneiss is a common and widely distributed type of Rock formed by high-grade regional metamorphic rock processes from pre-existing formations that were originally either igneous rock or Sedimentary rock rocks....
, and schist

Schist

The schists form a group of Erins metamorphic rocks, chiefly notable for the preponderance of lamellar minerals such as micas, Chlorite group, talc, hornblende, graphite, and others....
. It is the principal mineral of amphibolite

Amphibolite

Amphibolite is the name given to a Rock consisting mainly of hornblende amphibole, the use of the term being restricted, however, to metamorphic rocks....
s. Very dark brown to black hornblendes that contain titanium are ordinarily called basalt

Basalt

Basalt is a common extrusive volcanic rock. It is usually gray to black and fine-grained due to rapid cooling of lava at the surface of a planet....
ic hornblende, from the fact that they are usually a constituent of basalt and related rocks. Hornblende alters easily to chlorite

Chlorite group

The chlorites are a group of Silicate minerals minerals. Chlorites can be described by the following four Solid solution based on their chemistry via substitution of the following four elements in the silicate lattice; Mg, Fe, Ni, and Mn....
and epidote

Epidote

Epidote is a calcium aluminium iron Silicate minerals mineral, Ca2Al2O, crystallizing in the monoclinic system. Well-developed crystals are of frequent occurrence: they are commonly prismatic in habit, the direction of elongation being perpendicular to the single plane of symmetry....
. A variety of hornblende that contains less than 5% of iron oxide

Iron oxide

Iron oxides are chemical compounds composed of iron and oxygen. Altogether, there are sixteen known iron oxides and oxyhydroxides....
s is gray to white in color and named edenite, from its locality in Edenville, New York

New York

The State of New York is a U.S. state in the Mid-Atlantic States and Northeastern United States regions of the United States and is the nation's List of U.S....
. Other minerals in the hornblende series include: pargasite

Pargasite

Pargasite is a complex Silicate mineral mineral with formula NaCa24AlO222.It was first described for an occurrence in Pargas, Finland in 1814 and named for the locality....
, hastingsite and tschermakite

Tschermakite

The endmember hornblende tschermakite is a calcium rich monoclinic amphibole mineral. It is frequently synthesized along with its ternary solid solution series members tremolite and cummingtonite so that the thermodynamic properties of its assemblage can be applied to solving other solid solution series from a variety of amphibole minerals....
.

The word hornblende is derived from the German

German language

German is a West Germanic languages, thus related to and classified alongside English language and Dutch language. It is one of the world's world language and the most widely spoken mother tongue in the European Union....
horn and blenden, to 'blind' or 'dazzle'. The term blende is often used to refer to a brilliant non-metallic lustre

Lustre (mineralogy)

Lustre is a description of the way light interacts with the surface of a crystal, rock , or mineral. For example, a diamond is said to have an adamantine lustre and pyrite is said to have a metallic lustre....
, for example, zincblende

Zinc

Zinc is a metallic chemical element with the symbol Zn and atomic number 30. It is a first-row transition metal of the group 12 element of the periodic table....
and pitchblende, a lustrous form of uraninite

Uraninite

Uraninite is a radioactive, uranium-rich mineral and ore with a chemical composition that is largely uranium dioxide, but also contains uranium trioxide and oxides of lead, thorium, and rare earth elements....
.

Hornblende

See also