Metals constitute a large portion of the Periodic Table of elements. Their combinations with each other and the other elements result in the minerals that compose rocky-objects.

These specimens are some of the most easily recognizable, dramatic and highly sought after silver specimens from the Western Hemisphere. Credit: Robert Lavinsky.

Generally, the transition metals constitute the periodic table of elements from groups 3-12, beginning with scandium (Sc) and ending with element number 112 Copernicium.

Usually, these and the other metals are divided into several subgroups for specific purposes:

  1. Metalloids - gallium (Ga) through selenium (Se) and cadmium (Cd) through tellurium (Te).
  2. Alkaline earth metals - group 2: beryllium (Be) through radium (Ra).
  3. Alkali metals - group 1: lithium (Li) through francium (Fr).
  4. Body-centered cubic metals - titanium (Ti) through chromium (Cr), zirconium (Zr) through molybdenum (Mo), and hafnium (Hf) through tungsten (W).
  5. Heavy metals - mercury (Hg) through polonium (Po).
  6. Lanthanides - lanthanum (La) through lutetium (Lu), also called the rare-earths.
  7. Precious metals - ruthenium (Ru) through silver (Ag) and rhenium (Re) through gold (Au).
  8. Siliconides.
  9. Transition metals are often restricted to manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), and zinc (Zn).
  10. Transuranics - neptunium (Np) through Roentgenium (Rg) and Copernicium (Cn).

The category of metals also includes aluminum, scandium (Sc), yttrium (Y), technetium (Tc), and the actinides.



In general the close-packing structures: face-centered cubic (fcc) and hexagonal close-packed (hcp) are the most efficient way to pack a bunch of hard, equal-sized marbles into the smallest space. Metals often occur in these structures and as body-centered cubics which are not close-packed structures.

Actinide minerals

Uranophane is a calcium uranium silicate hydrate mineral. Credit: United States Geological Survey.

Uranophane Ca(UO2)2(SiO3OH)2·5H2O is a rare calcium uranium [nesosilicate] hydrate mineral that forms from the oxidation of uranium bearing minerals. Uranophane is also known as uranotile. It has a yellow color and is radioactive.

Def. any of the 14 radioactive elements of the periodic table that are positioned under the lanthanides to which they have similar chemistry is called an actinide in inorganic chemistry.

Alkali metal minerals

This is a proposed or tentative phase diagram for hydrogen with temperature and pressure. Credit: Isaac Silvera.

The alkali metals are from group 1 of the Periodic Table and include hydrogens.

Alkaline earth metal minerals

This is a pressure-temperature phase diagram for barium. Credit: David A. Young, ERDA.

Barium is bcc (α-Ba) at room temperature as the phase diagram on the left indicates. It does change to an hcp structure at high pressures and temperatures.

Native barium is not known to occur on the surface of the Earth.

Def. any oxide of the elements of group II of the periodic table; they are not as basic as the alkalis, and not so soluble in water is called an alkaline earth.

Def. any of the elements of group II of the periodic table; they are low-density metals that react readily with water to form strongly basic hydroxides, and with many acids to form salts is called an alkaline earth metal.

Aluminide minerals

Near the top center of this image is a gray reflective flake of native aluminum. Credit: Vasil Arnaudov.

The aluminides are those naturally occurring minerals with a high atomic % aluminum.

In the image on the right of a flake of native aluminum, the scale bar = 1 mm.

Aluminium is the third most abundant element (after oxygen and silicon) in the Earth's crust, and the most abundant metal there. It makes up about 8% by mass of the crust, though it is less common in the mantle below.

Def. any intermetallic compound of aluminium and a more electropositive element is an aluminide in chemistry.

Body-centered cubic metal minerals

This is an iron-titanium phase diagram. Credit: Hirokai.

"Microbeam analysis of eclogites from the ultrahigh-pressure metamorphic belt in Dabieshan, China has revealed native titanium inclusions in garnets of coesite eclogite. The inclusions are about 10 μm in size, have a submetallic luster from the thin oxidation film on the surface, and are brown under reflected light."[1]

Titanium "undergoes a phase transformation (hcp to bcc) at 882 °C [5]."[2]

As the phase diagram on the left indicates, there is a miscibility gap between bcc iron (α-Fe) and hcp (α-Ti) up to about 800°C.

Carbonide minerals

The mineral Lonsdaleite is made from carbon with a different arrangement than diamond. Credit: payam.

"The mineral Lonsdaleite is a translucent, brownish yellow and is made from the atoms of carbon but the arrangement of these atoms is different from the arrangement of carbon atoms in a diamond. [...] The mineral is very rare and is formed naturally whenever [...] graphite containing meteorites fall on the earth and hit the surface."[3]

"Found in the Canyon Diablo and Goalpara meteorites."[4]

Def. any

  1. binary compound of carbon and a more electropositive element,
  2. the polyatomic ion C22−, or any of its salts,
  3. the monatomic ion C4−, or any of its salts,
  4. a carbon-containing alloy or doping of a metal or semiconductor, such as steel,
  5. an archaic form of carbide, or
  6. naturally occurring minerals composed of 50 atomic percent, or more, carbon,

are called carbonides.

Def. minerals with greater than 25 at % carbon but less than 50 at % carbon are called carbonide-like minerals.

Chalcogen minerals

These are native selenium needles from Katharine mine, Radvanice, Czech Republic. Credit: Asahi.

In the magnified image of the sample on the right are native selenium needles.

Def. any element of group 16 of the periodic table is called a chalcogen in inorganic chemistry.

Metalloid minerals

Native arsenic such as this specimen is found in silver ore veins. Credit: Amethyst Galleries, Inc.

Native arsenic such as in the image on the right occurs in silver ore veins.

Def. an element intermediate in properties between that of a metal and a nonmetal; especially one that exhibits the external characteristics of a metal, but behaves chemically more as a nonmetal is called a metalloid.

Precious metal minerals

This very elaborate, 3-dimensional cluster of gold shows complex and minute crystallization patterns, and is overall hackly in texture. Credit: Robert Lavinsky.

Precious metals are usually rare, chemically relatively inert, and often colorful.

They are transition metals ruthenium (Ru) through silver (Ag) and rhenium (Re) through gold (Au).

Transition metal minerals

A large, sculptural specimen of penny-bright copper is from Arizona. Credit: Robert Lavinsky.

The most advantageous form for copper is native copper.

On the right is a large, sculptural specimen of penny-bright copper from Arizona.



"Based on the observation of the long-lived isotopes of roentgenium, 261Rg and 265Rg (Z = 111, t1/2 ≥ 108 y) in natural Au, an experiment was performed to enrich Rg in 99.999% Au. 16 mg of Au were heated in vacuum for two weeks at a temperature of 1127°C (63°C above the melting point of Au). The content of 197Au and 261Rg in the residue was studied with high resolution inductively coupled plasma-sector field mass spectrometry (ICP-SFMS). The residue of Au was 3 × 10−6 of its original quantity. The recovery of Rg was a few percent. The abundance of Rg compared to Au in the enriched solution was about 2 × 10−6, which is a three to four orders of magnitude enrichment."[5]


  1. Other elements can occur in the metal-like structures as molecules.

See also



  1. Jing Chen; Jiliang Li; Jun Wu (30 April 2000). "Native titanium inclusions in the coesite eclogites from Dabieshan, China". Earth and Planetary Science Letters 177 (3-4): 237-40. doi:10.1016/S0012-821X(00)00057-1. Retrieved 2015-08-19. 
  2. B.B. Panigrahi; M.M. Godkhindi; K. Das; P.G. Mukunda; P. Ramakrishnan (15 April 2005). "Sintering kinetics of micrometric titanium powder". Materials Science and Engineering: A 396 (1-2): 255-62. doi:10.1016/j.msea.2005.01.016. Retrieved 2015-08-19. 
  3. payam (30 July 2013). Top 10 Hardest Material in the world. Help Tips. Retrieved 2015-07-30. 
  4. Willard Lincoln Roberts; George Robert Rapp Jr.; Julius Weber (1974). Encyclopedia of Minerals. New York, New York, USA: Van Nostrand Reinhold Company. pp. 121-2. ISBN 0-442-26820-3. 
  5. A. Marinov; A. Pape; D. Kolb; L. Halicz; I. Segal; N. Tepliakov; R. Brandt (2011). "Enrichment of the Superheavy Element Roentgenium (Rg) in Natural Au". International Journal of Modern Physics E 20 (11): 2391-2401. doi:10.1142/S0218301311020393. Retrieved 2014-04-08.