Nu metal (also known as nü-metal,^[4] aggro-metal,^[1][5] neo-metal^[6] or new metal) is a subgenre^[7] of heavy metal.^{[4][8][9][10]} It is a fusion genre^[9] which combines elements of metal with other genres, including hip hop and grunge. It is classed as part of alternative metal.^[1][11]

Characteristics[link]

Rock bands of the 1980s and 1990s including Faith No More, Red Hot Chili Peppers, Jane's Addiction, Nirvana, Tool and Rage Against the Machine have been identified as laying groundwork for the development of nu metal by popularising elements of the genre, such as combining aggressive riffs with pop structures and drawing influence from a variety of genres within and outside of heavy metal.^[12][13]

Bands associated with nu metal derive influence from a variety of diverse styles, including electronic music, funk, glam metal, gothic rock, grunge, hardcore punk, hip hop, industrial metal, jazz, post-punk and synthpop.^{[1][2][9][14][15]} Nu metal also derives influences from multiple sub-genres of heavy metal including rap metal, funk metal, alternative metal and thrash metal.^[1][2][9]

Nu metal music is mostly syncopated and based on riffs.^[4] Mid-song breakdowns and lack of solos contrasts it with other metal sub-genres.^[4] Another contrast with other metal sub-genres is its emphasis on rhythm, tending to more elements of groove metal in rhythm.^[9] Similarities with other heavy metal sub-genres include its use of common time, distorted guitars, power chords and note structures primarily revolving around Dorian, Aeolian or Phrygian modes.^[4]

Many nu metal bands use seven-string guitars over traditional six-string guitars.^[2] Seven-string guitars, which are sometimes downtuned^[10] to increase heaviness, resulted in bass guitarists using five-string and six string instruments.^[2] DJs are also sometimes used for additional rhythmic instrumentation such as music sampling, scratching and electronic backgrounds.^[2]

Nu metal vocal styles range between melodic singing, rapping, screaming and death growling, sometimes using multiple of these styles within one song. The lyrics of many nu metal bands focus on pain and personal alienation rather than the themes of other metal subgenres.^[2][15] Q Magazine stated that many of the genre's "leading lights [focused on] abandonment issues they should have left behind on their first day of big school".

Nu metal uses the traditional pop structure of verses, choruses and bridges, contrasting it with other metal genres such as thrash and death metal.^[16] Nu metal fashion can include baggy shirts, cargo pants, sweatpants, body piercings, tattoos, and in some cases jumpsuits and sweatsuits.^[17][18]

History[link]

The origins of the term are often attributed to the work of producer Ross Robinson, sometimes called "The Godfather of Nu Metal".^[12] Many of the first nu metal bands came from California,^[19] like Korn, which pioneered the nu metal sound with the release of their demo album in 1993,^[20] and Deftones. Other influential bands are Staind from Massachusetts, Limp Bizkit from Florida,^[11] and Slipknot from Iowa. The aggressive riff of Korn, the rap rock of Limp Bizkit and the acoustic ballads of Staind created the sonic template for nu metal.^[11] Nu metal gained mainstream success through MTV and Ozzy Osbourne's 1995 introduction of Ozzfest, which led the media to talk of a resurgence of heavy metal.^[21]

By the latter 90s, nu metal bands were playing a combination of thrash metal, hip hop, industrial, hardcore punk and grunge.^[1] Established artists such as Sepultura,^[22] Slayer,^[23] Vanilla Ice^[24] and Machine Head^[25] released albums which drew from the style. In Sound of the Beast: The Complete Headbanging History of Heavy Metal, Ian Christie wrote that the genre demonstrated that "pancultural metal could pay off".^[26] However, some fans of old metal did not fully embrace the style.^[26] The 30th anniversary of Woodstock featured nu metal bands, notably Korn and Limp Bizkit.^[27]

Limp Bizkit's 1999 album Significant Other reached number 1 on the Billboard 200, selling 643,874 copies in its first week of release.^[28] In its second week of release, the album sold 335,000 copies.^[28] In 2000, Limp Bizkit's followup album, Chocolate Starfish and the Hot Dog Flavored Water, set a record for highest week-one sales of a rock album with over one million copies sold in the U.S. in its first week of release, with 400,000 of those sales coming on its first day, making it the fastest-selling rock album ever, breaking the world record held for seven years by Pearl Jam's Vs.^[29] The same year, Papa Roach's major label debut, Infest became a platinum hit.^[30]

In 2002, critics began claiming that nu metal's mainstream popularity was declining,^[31] citing the fact that Korn's long awaited fifth album Untouchables, and Papa Roach's third album Lovehatetragedy, did not sell as well as their previous releases, and nu metal bands were played less frequently on radio stations and MTV began focusing on pop punk and emo.^[32] By the mid-2000s, metalcore and the New Wave of American Heavy Metal had become the dominant metal subgenre in both the mainstream and within metal audiences.^[33]

Despite the lesser radio play and popularity, some nu metal bands still gain commercial success. Korn's 9th studio album, Korn III: Remember Who You Are, sold 63,000 copies during its first week in the US, landing at number two on the Billboard 200.^[34] As of December 6, 2011, the album has sold 185,000 units in the U.S.^[35] and received positive reviews from critics. In 2011, Limp Bizkit's long awaited sixth studio album, Gold Cobra, was a commercial success, selling 63,000 copies in the United States and peaking at number 16 on the Billboard 200 and the album has received mostly positive reviews.^[36][37] Also in 2011, Staind's self-titled album debuted at number 5 on the Billboard 200, with first sales week of 47,000 copies, making the fifth consecutive top-five album for the band.^[38] As of November 19, 2011, it has sold over 100,000 copies and received some of the most positive reviews the band has ever got from music critics.

See also[link]

• Family Values Tour
• List of nu metal bands

References[link]

External links[link]

• MTV.com: Nu Metal Meltdown
• Songfacts.com: Why Does Everybody Hate Nu-Metal?

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A metal (from Greek "μέταλλον" – métallon, "mine, quarry, metal"^[1][2]) is an element, compound, or alloy that is a good conductor of both electricity and heat. Metals are usually malleable and shiny, that is they reflect most of incident light.^[3] In a metal, atoms readily lose electrons to form positive ions (cations). Those ions are surrounded by de-localized electrons, which are responsible for the conductivity. The solid thus produced is held by electrostatic interactions between the ions and the electron cloud, which are called metallic bonds.^[4]

Definition[link]

This unreferenced section requires citations to ensure verifiability.

Metals are sometimes described as an arrangement of positive ions surrounded by a sea of delocalized electrons. Metals occupy the bulk of the periodic table, while non-metallic elements can only be found on its right-hand side. A diagonal line, drawn from boron (B) to polonium (Po), separates the metals from the nonmetals. Most elements on this line are metalloids, sometimes called semiconductors. This is because these elements exhibit electrical properties common to both conductors and insulators. Elements to the lower left of this division line are called metals, while elements to the upper right of the division line are called nonmetals.

An alternative definition of metal refers to the band theory. If one fills the energy bands of a material with available electrons and ends up with a top band partly filled then the material is a metal. This definition opens up the category for metallic polymers and other organic metals. These synthetic materials often have the characteristic silvery gray reflectiveness (luster) of elemental metals.

Astronomy[link]

In the specialized usage of astronomy and astrophysics, the term "metal" is often used to refer collectively to all elements other than hydrogen or helium, including substances as chemically non-metallic as neon, fluorine, and oxygen. Nearly all the hydrogen and helium in the Universe was created in Big Bang nucleosynthesis, whereas all the "metals" were produced by nucleosynthesis in stars or supernovae. The Sun and the Milky Way Galaxy are composed of roughly 74% hydrogen, 24% helium, and 2% "metals" (the rest of the elements; atomic numbers 3–118) by mass.^[5]

The concept of a metal in the usual chemical sense is irrelevant in stars, as the chemical bonds that give elements their properties cannot exist at stellar temperatures.

Properties[link]

Chemical[link]

Metals are usually inclined to form cations through electron loss,^[4] reacting with oxygen in the air to form oxides over changing timescales (iron rusts over years, while potassium burns in seconds). Examples:

4 Na + O₂ → 2 Na₂O (sodium oxide)

2 Ca + O₂ → 2 CaO (calcium oxide)

4 Al + 3 O₂ → 2 Al₂O₃ (aluminium oxide).

The transition metals (such as iron, copper, zinc, and nickel) take much longer to oxidize. Others, like palladium, platinum and gold, do not react with the atmosphere at all. Some metals form a barrier layer of oxide on their surface which cannot be penetrated by further oxygen molecules and thus retain their shiny appearance and good conductivity for many decades (like aluminium, magnesium, some steels, and titanium). The oxides of metals are generally basic, as opposed to those of nonmetals, which are acidic.

Painting, anodizing or plating metals are good ways to prevent their corrosion. However, a more reactive metal in the electrochemical series must be chosen for coating, especially when chipping of the coating is expected. Water and the two metals form an electrochemical cell, and if the coating is less reactive than the coatee, the coating actually promotes corrosion.

Physical[link]

Gallium crystals

Metals in general have high electrical conductivity which depends on their valency of ions, thermal conductivity, luster and density, and the ability to be deformed under stress without cleaving.^[4] While there are several metals that have low density, hardness, and melting points, these (the alkali and alkaline earth metals) are extremely reactive, and are rarely encountered in their elemental, metallic form. Optically speaking, metals are opaque, shiny and lustrous. This is because visible lightwaves are not readily transmitted through the bulk of their microstructure. The large number of mobile electrons in any typical metallic solid (element or alloy) is responsible for the fact that they can never be categorized as transparent materials.

The majority of metals have higher densities than the majority of nonmetals.^[4] Nonetheless, there is wide variation in the densities of metals; lithium is the least dense solid element and osmium is the densest. The metals of groups I A and II A are referred to as the light metals because they are exceptions to this generalization.^[4] The high density of most metals is due to the tightly packed crystal lattice of the metallic structure. The strength of metallic bonds for different metals reaches a maximum around the center of the transition metal series, as those elements have large amounts of delocalized electrons in tight binding type metallic bonds. However, other factors (such as atomic radius, nuclear charge, number of bonding orbitals, overlap of orbital energies, and crystal form) are involved as well.^[4]. Most non-ferrous metals can be recycled many times during their life cycle.

Electrical[link]

The electrical and thermal conductivity of metals originate from the fact that in the metallic bond, the outer electrons of the metal atoms form a gas of nearly free electrons, moving as an electron gas in a background of positive charge formed by the ion cores. Good mathematical predictions for electrical conductivity, as well as the electrons' contribution to the heat capacity and heat conductivity of metals can be calculated from the free electron model, which does not take the detailed structure of the ion lattice into account.

When considering the exact band structure and binding energy of a metal, it is necessary to take into account the positive potential caused by the specific arrangement of the ion cores – which is periodic in crystals. The most important consequence of the periodic potential is the formation of a small band gap at the boundary of the Brillouin zone. Mathematically, the potential of the ion cores can be treated by various models, the simplest being the nearly free electron model.

Mechanical[link]

Mechanical properties of metals include ductility, which is largely due to their inherent capacity for plastic deformation. Reversible elastic deformation in metals can be described by Hooke's Law for restoring forces, where the stress is linearly proportional to the strain. Forces larger than the elastic limit, or heat, may cause a permanent (irreversible) deformation of the object, known as plastic deformation or plasticity. This irreversible change in atomic arrangement may occur as a result of:

• The action of an applied force (or work). An applied force may be tensile (pulling) force, compressive (pushing) force, shear, bending or torsion (twisting) forces.

• A change in temperature (heat). A temperature change may affect the mobility of the structural defects such as grain boundaries, point vacancies, line and screw dislocations, stacking faults and twins in both crystalline and non-crystalline solids. The movement or displacement of such mobile defects is thermally activated, and thus limited by the rate of atomic diffusion.

Hot metal work from a blacksmith.

Viscous flow near grain boundaries, for example, can give rise to internal slip, creep and fatigue in metals. It can also contribute to significant changes in the microstructure like grain growth and localized densification due to the elimination of intergranular porosity. Screw dislocations may slip in the direction of any lattice plane containing the dislocation, while the principal driving force for "dislocation climb" is the movement or diffusion of vacancies through a crystal lattice.

In addition, the nondirectional nature of metallic bonding is also thought to contribute significantly to the ductility of most metallic solids. When the planes of an ionic bond slide past one another, the resultant change in location shifts ions of the same charge into close proximity, resulting in the cleavage of the crystal; such shift is not observed in covalently bonded crystals where fracture and crystal fragmentation occurs.^[6]

Alloys[link]

An alloy is a mixture of two or more elements in solid solution in which the major component is a metal. Most pure metals are either too soft, brittle or chemically reactive for practical use. Combining different ratios of metals as alloys modifies the properties of pure metals to produce desirable characteristics. The aim of making alloys is generally to make them less brittle, harder, resistant to corrosion, or have a more desirable color and luster. Of all the metallic alloys in use today, the alloys of iron (steel, stainless steel, cast iron, tool steel, alloy steel) make up the largest proportion both by quantity and commercial value. Iron alloyed with various proportions of carbon gives low, mid and high carbon steels, with increasing carbon levels reducing ductility and toughness. The addition of silicon will produce cast irons, while the addition of chromium, nickel and molybdenum to carbon steels (more than 10%) results in stainless steels.

Other significant metallic alloys are those of aluminium, titanium, copper and magnesium. Copper alloys have been known since prehistory—bronze gave the Bronze Age its name—and have many applications today, most importantly in electrical wiring. The alloys of the other three metals have been developed relatively recently; due to their chemical reactivity they require electrolytic extraction processes. The alloys of aluminium, titanium and magnesium are valued for their high strength-to-weight ratios; magnesium can also provide electromagnetic shielding^{[citation needed]}. These materials are ideal for situations where high strength-to-weight ratio is more important than material cost, such as in aerospace and some automotive applications.

Alloys specially designed for highly demanding applications, such as jet engines, may contain more than ten elements.

Categories[link]

Base metal[link]

Zinc, a base metal, reacting with an acid

In chemistry, the term base metal is used informally to refer to a metal that oxidizes or corrodes relatively easily, and reacts variably with dilute hydrochloric acid (HCl) to form hydrogen. Examples include iron, nickel, lead and zinc. Copper is considered a base metal as it oxidizes relatively easily, although it does not react with HCl. It is commonly used in opposition to noble metal.

In alchemy, a base metal was a common and inexpensive metal, as opposed to precious metals, mainly gold and silver. A longtime goal of the alchemists was the transmutation of base metals into precious metals.

In numismatics, coins used to derive their value primarily from the precious metal content. Most modern currencies are fiat currency, allowing the coins to be made of base metal.

Ferrous metal[link]

The term "ferrous" is derived from the Latin word meaning "containing iron". This can include pure iron, such as wrought iron, or an alloy such as steel. Ferrous metals are often magnetic, but not exclusively.

Noble metal[link]

Noble metals are metals that are resistant to corrosion or oxidation, unlike most base metals. They tend to be precious metals, often due to perceived rarity. Examples include gold, platinum, silver and rhodium.

Precious metal[link]

A gold nugget

A precious metal is a rare metallic chemical element of high economic value.

Chemically, the precious metals are less reactive than most elements, have high luster and high electrical conductivity. Historically, precious metals were important as currency, but are now regarded mainly as investment and industrial commodities. Gold, silver, platinum and palladium each have an ISO 4217 currency code. The best-known precious metals are gold and silver. While both have industrial uses, they are better known for their uses in art, jewelry, and coinage. Other precious metals include the platinum group metals: ruthenium, rhodium, palladium, osmium, iridium, and platinum, of which platinum is the most widely traded.

The demand for precious metals is driven not only by their practical use, but also by their role as investments and a store of value. Palladium was, as of summer 2006, valued at a little under half the price of gold, and platinum at around twice that of gold. Silver is substantially less expensive than these metals, but is often traditionally considered a precious metal for its role in coinage and jewelry.

Extraction[link]

Metals are often extracted from the Earth by means of mining, resulting in ores that are relatively rich sources of the requisite elements. Ore is located by prospecting techniques, followed by the exploration and examination of deposits. Mineral sources are generally divided into surface mines, which are mined by excavation using heavy equipment, and subsurface mines.

Once the ore is mined, the metals must be extracted, usually by chemical or electrolytic reduction. Pyrometallurgy uses high temperatures to convert ore into raw metals, while hydrometallurgy employs aqueous chemistry for the same purpose. The methods used depend on the metal and their contaminants.

When a metal ore is an ionic compound of that metal and a non-metal, the ore must usually be smelted — heated with a reducing agent — to extract the pure metal. Many common metals, such as iron, are smelted using carbon as a reducing agent. Some metals, such as aluminium and sodium, have no commercially practical reducing agent, and are extracted using electrolysis instead.^[7][8]

Sulfide ores are not reduced directly to the metal but are roasted in air to convert them to oxides.

Recycling of metals[link]

Demand for metals is closely linked to economic growth. During the 20th century, the variety of metals uses in society grew rapidly. Today, the development of major nations, such as China and India, and advances in technologies, are fuelling ever more demand. The result is that mining activities are expanding, and more and more of the world’s metal stocks are above ground in use, rather than below ground as unused reserves. An example is the in-use stock of copper. Between 1932 and 1999, copper in use in the USA rose from 73g to 238g per person.^[9]

Metals are inherently recyclable, so in principle, can be used over and over again, minimizing these negative environmental impacts and saving energy at the same time. For example, 95% of the energy used to make aluminium from bauxite ore is saved by using recycled material.^[10] However, levels of metals recycling are generally low. In 2010, the International Resource Panel, hosted by the United Nations Environment Programme (UNEP) published reports on metal stocks that exist within society^[11] and their recycling rates.^[12]

The report authors observed that the metal stocks in society can serve as huge mines above ground. However, they warned that the recycling rates of some rare metals used in applications such as mobile phones, battery packs for hybrid cars and fuel cells are so low that unless future end-of-life recycling rates are dramatically stepped up these critical metals will become unavailable for use in modern technology.

Metallurgy[link]

Metallurgy is a domain of materials science that studies the physical and chemical behavior of metallic elements, their intermetallic compounds, and their mixtures, which are called alloys.

Applications[link]

Some metals and metal alloys possess high structural strength per unit mass, making them useful materials for carrying large loads or resisting impact damage. Metal alloys can be engineered to have high resistance to shear, torque and deformation. However the same metal can also be vulnerable to fatigue damage through repeated use or from sudden stress failure when a load capacity is exceeded. The strength and resilience of metals has led to their frequent use in high-rise building and bridge construction, as well as most vehicles, many appliances, tools, pipes, non-illuminated signs and railroad tracks.

The two most commonly used structural metals, iron and aluminium, are also the most abundant metals in the Earth's crust.^[13]

Metals are good conductors, making them valuable in electrical appliances and for carrying an electric current over a distance with little energy lost. Electrical power grids rely on metal cables to distribute electricity. Home electrical systems, for the most part, are wired with copper wire for its good conducting properties.

The thermal conductivity of metal is useful for containers to heat materials over a flame. Metal is also used for heat sinks to protect sensitive equipment from overheating.

The high reflectivity of some metals is important in the construction of mirrors, including precision astronomical instruments. This last property can also make metallic jewelry aesthetically appealing.

Some metals have specialized uses; radioactive metals such as uranium and plutonium are used in nuclear power plants to produce energy via nuclear fission. Mercury is a liquid at room temperature and is used in switches to complete a circuit when it flows over the switch contacts. Shape memory alloy is used for applications such as pipes, fasteners and vascular stents.

Trade[link]

Metal and ore imports in 2005

The World Bank reports that China was the top importer of ores and metals in 2005 followed by the U.S.A. and Japan.^[14]

History[link]

The nature of metals has fascinated mankind for many centuries, because these materials provided people with tools of unsurpassed properties both in war and in their preparation and processing.

Sterling gold and silver are known to man since the Stone Age. Lead and silver were molten down from ores since the fourth millennium BC.^[15]

See also[link]

References[link]

Look up metal in Wiktionary, the free dictionary.

Wikimedia Commons has media related to: Metals

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