< Minerals
This massive native arsenic with quartz and calcite is from Ste. Marie-aux-mines, Alsace, France. Credit: Aram Dulyan.

Metalloids are elements whose properties are intermediate between metals and solid nonmetals or semiconductors.

A variety of elements are often considered metalloids:

  1. boron, considered here in the boronides,
  2. aluminum, a face-centered cubic metal, considered in the aluminides,
  3. silicon, here in the siliconides,
  4. gallium (it can occur in the liquid state as a mineraloid),
  5. germanium,
  6. arsenic,
  7. selenium, also included in the chalcogens,
  8. indium,
  9. tin,
  10. antimony,
  11. tellurium, also included in the chalcogens,
  12. polonium, considered as among the heavy metals and
  13. astatine, here is with the halogens.

Minerals

Each of the metalloids, in the native or elemental form has at least one crystal structure, but these structures may not be the usual cubic structures: face-centered cubic or body-centered cubic that metals often occur in.

Galliums

This is an example of gallite from Namibia. Credit: Hudson Institute of Mineralogy.

While native gallium would be the best source of gallium, it apparently does not occur on Earth.

Gallite (CuGaS2) is 25 at % gallium.

Germaniums

This sample of germanite is displayed in the Smithsonian Museum of Natural History. Credit: R Nave.

The sample of germanite on the right has a composition of Cu26Fe4Ge4S32. Generally, germanite has a composition closer to Cu3(Ge, Ga, Fe, Zn) (S,As)4.[1] "This sample also contains tennantite."[2]

Arsenics

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 and at the top of this resource occurs in silver ore veins.

Allemontites

Allemontite (with Pen for scale) is from the mineral collection of Brigham Young University Department of Geology, Provo, Utah. Credit: Andrew Silver,USGS.
Allemontite specimen is from Příbram, Central Bohemia Region, Bohemia (Böhmen; Boehmen), Czech Republic. Credit: Robert Lavinsky.

Allemontite is a native alloy of arsenic and antimony, with a composition of AsSb.[1]

The first example on the right is from the mineral collection of Brigham Young University Department of Geology, Provo, Utah.

The second is from Příbram, Central Bohemia Region, Bohemia (Böhmen; Boehmen), Czech Republic.

As a natural source of arsenic, it has 50 at % arsenic.

Seleniums

Selenium (native) with pen for scale is from the mineral collection of Brigham Young University Department of Geology, Provo, Utah. Credit: Andrew Silver, USGS.
The dark gray mineral in the yellow sandstone is native selenium. Credit: James St. John.

On the right is a photograph of native selenium from the mineral collection of Brigham Young University Department of Geology, Provo, Utah.

The second image down on the right shows dark gray selenium in sandstone from Westwater Canyon Section 23 Mine Grants, New Mexico.

Indiums

These pieces of native indium are from Eastern Transbaikal, Russia. Credit: Michael Scott.

On the right are microprobe fragments of native indium from Eastern Transbaikal, Russia. The electron microprobe confirms that indium is the only component of the metallic phase.

Tins

This small piece of native tin is from the Badiko District, Bauchi State, Nigeria. Credit: Robert Lavinsky.
This is native tin from a porphyry copper deposit in the Bingham Deposit, Utah, USA. Credit: Alison Roberts.

Native tin such as in the images on the right occurs in two crystal forms: α-Sn (cubic) and β-Sn (tetragonal).[1]

Antimonies

This is massive antimony with oxidation products from Arechuybo, Mexico. Credit: Aram Dulyan at the Natural History Museum, London.
The native antimony crystals, lustrous and nicely striated in part, range up to 0.5 cm in size. Credit: Robert Lavinsky.

Native antimony such as occurs in the rock on the upper right with its various oxidation products is crystalline in the hexagonal system.

The second image shows hexagonal crystals with metallic luster.

Telluriums

This is a native tellurium crystal from the Emperor Mine, Vatukoula, Tavua Gold Field, Viti Levu, Fiji. Credit: Robert Stravinsky.

On the right is an example of native tellurium from the Emperor Mine, Vatukoula, Tavua Gold Field, Viti Levu, Fiji.

Hypotheses

  1. Traditional metalloid recovery processes applicable on Earth may not be so applicable on other astronomical objects such as Mars or the Moon.

See also

References

  1. 1 2 3 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.
  2. ↑ R Nave (17 August 2015). Germanite. Washington, DS USA: Smithsonian Museum of Natural History. Retrieved 2015-08-17.
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