Minerals/Chalcogens

< Minerals
The image shows native sulfur, yellow, and calcite crystals, clear or white. Credit: Didier Descouens.

The chalcogens are the elements of group 16 of the Periodic Table. These include oxygen (O), sulfur (S), selenium (Se), tellurium (Te), polonium (Po), and livermorium (Lv).

Chalcogen minerals are those with a high atomic percent of chalcogens.

Oxygens

Native oxygen does not exist as a mineral on the surface of the Earth.

Oxygen-based minerals are those minerals with more than 25 at % oxygen. Oxygen often combines with most of the other elements in the periodic table.

Oxidanes

These are minerals composed of or more than 25 at % H2O.

Abernathyites

Pale yellow abernathyite crystals, around the edges, and green heinrichite crystals, in the center of the clusters, can be seen. Credit: Leon Hupperichs.

Abernathyite has the chemical formula KUO2AsO4·3H2O.[1] There are three oxygen groups in this mineral:

  1. UO2,
  2. AsO4, and
  3. 3H2O.

Each of these form mineral groups:

  1. uraninites, 16.7 at %,
  2. arsenates, 27.8 at %, and
  3. oxidanes, 50.0 at %, with the atomic percentages included.

On these bases, abernathyite is both an arsenate (27.8 at %) and an oxidane (50.0 at %). It is also an oxygenide at 50.0 at % oxygen. In terms of oxides, abernathyite is about 60.0 molecular percent H2O. While potassium does not occur on the surface of the Earth as native potassium, in abernathyite, the atom of potassium links to oxygens from all three oxides.

Hydroxides

Hydroxide minerals contain more than 25 at % OH.

Aeschynites

Aeschynite has the chemical formula (Ce, Ca, Fe, Th)(Ti, Nb)2(O, OH)6.[1]

Here there are two oxygen groups:

  1. O, oxygenides, from 11.1 to 55.6 at % likely, and
  2. OH, hydroxides, from 55.6 to 11.1 at % likely.

Silicates

Silicates contain more than 25 at % silicates.

Afwillites

The clear to white small crystals on the rock are afwillite. Credit: Dave Dyet.

Afwillite has had a couple of formulas:

  1. Ca3Si2O4(OH)6,[1] and
  2. Ca3(HSiO4)2·2H2O.[2]

Structurally, afwillite is a nesosilicate with isolated SiO4 tetrahedra.

Afwillite has two oxides:

  1. 2SiO4, Silicates, and
  2. 2H2O, oxidanes, with each having about 50 molecular %.

Calcium does not occur as native calcium. Here it links to the oxygens in the silicate tetrahedra and the oxidanes. Afwillite is 47.6 at % silicate and 28.6 at % oxidane.

Carbonates

Carbonates contain more than 25 at % CO3.

Calcites

Large crystal of Calcite is on display. Credit: Alkivar, National Museum of Natural History.

Calcite has the chemical formula CaCO3.[1]

Calcite contains one oxide: CO3, or carbonate. It is just less than 100 molecular % carbonate and 80 at % carbonate.

Sulfurs

This shows sulfur crystals from the Smithsonian Institution. Credit: Deglr6328.
Native liquid sulfur in this photograph is red. Credit: National Iranian Gas Company.

Native sulfur occurs on the surface of the Earth.

At volcanic locations, native liquid sulfur can be seen flowing, such as in the image on the right, and it is red.

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

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.

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

Telluriums

This is a native tellurium crystal from the Emperor Mine, Vatukoula, Tavua Gold Field, Viti Levu, Fiji. Credit: Robert Stravinsky.
On the upper left of the rock is native tellurium. Credit: Theodore W. Gray.

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

On the left is an encrustation of native tellurium on the upper left portion of a rock.

Poloniums

This photograph shows a 210Po halo in biotite from the Buckhorn pegmatite. Credit: Lorence G. Collins.
Uranium roll front occurs in quartzose sandstone in the Cretaceous of Colorado, USA. Credit: James St. John.
This photo shows a fracture in biotite in which migrating 210Po and/or 210Pb ions have created damage to the biotite lattice parallel to the fracture. Credit: Lorence G. Collins.

α-Po crystallizes in a simple cubic lattice.[3]

Native polonium may occur in minerals like pitchblende due to the decay of uranium. But, when the uranium is chemically bound, the polonium is likely to be also.

β-Po has a rhombohedral (trigonal) crystal structure.[4]

"Solid diorite and gabbro rock, which had previously crystallized from magma, has been subjected to repeated cataclasis and recrystallization. This has happened without melting; and the cataclasis provided openings for the introduction of uranium-bearing fluids and for the modification of these rocks to granite by silication and cation deletion."[5]

"In uranium ore-fields the extra uranium provides an abundant source of inert radon gas; and it is this gas that diffuses in ambient fluids so that incipient biotite and fluorite crystallization is exposed to it. Radon (222Rn) decays and Po isotopes nucleate in the rapidly growing biotite (and fluorite) crystals whence they are positioned to produce the Po halos."[5]

On the lower right is a photograph showing radioactive decay halos along a crack in biotite.

On the left is an example of groundwater incursion that has moved through a nearby fault. The groundwater has picked up dissolved uranium compounds and moved downward through adjacent porous sandstones. Uraninite then precipitated around a tongue of groundwater, resulting in the roll front seen in the image on the left.

Livermoriums

Although generated by heavy ion bombardment, the short-lived radioisotopes are not known to occur naturally on the surface of the Earth.

Research

Hypothesis:

  1. Chalcogens such as the poloniums can occur as native polonium due to diffusion of radon gas with subsequent radioactive decay to polonium without chemical combination.
  2. The polonium atoms adhere to fracture surfaces and decay to produce Po halos.

Control groups

This is an image of a Lewis rat. Credit: Charles River Laboratories.

The findings demonstrate a statistically systematic change from the status quo or the control group.

“In the design of experiments, treatments [or special properties or characteristics] are applied to [or observed in] experimental units in the treatment group(s).[6] In comparative experiments, members of the complementary group, the control group, receive either no treatment or a standard treatment.[7]"[8]

Proof of concept

Def. a “short and/or incomplete realization of a certain method or idea to demonstrate its feasibility"[9] is called a proof of concept.

Def. evidence that demonstrates that a concept is possible is called proof of concept.

The proof-of-concept structure consists of

  1. background,
  2. procedures,
  3. findings, and
  4. interpretation.[10]

See also

References

  1. 1 2 3 4 Willard Lincoln Roberts, George Robert Rapp, Jr., and Julius Weber (1974). Encyclopedia of Minerals. 450 West 33rd Street, New York, New York 10001 USA: Van Nostrand Reinhold Company. pp. 693. ISBN 0-442-26820-3.
  2. ↑ Hudson Institute of Mineralogy (31 October 2015). "Afwillite". Hudson Institute of Mineralogy. Retrieved 2015-11-05.
  3. ↑ CST (20 November 2000). "The Simple Cubic Lattice". Washington, DC USA: The Naval Research Laboratory. Retrieved 2015-08-27.
  4. ↑ CSTPo (20 November 2000). "The A_i (beta Po) Structure". Washington, DC USA: The Naval Research Laboratory. Retrieved 2015-08-27.
  5. 1 2 Lorence G. Collins (3 February 1997). "Polonium Halos and Myrmekite in Pegmatite and Granite". Northridge, California USA: California State University, Northridge. Retrieved 2015-08-27.
  6. ↑ Klaus Hinkelmann, Oscar Kempthorne (2008). Design and Analysis of Experiments, Volume I: Introduction to Experimental Design (2nd ed.). Wiley. ISBN 978-0-471-72756-9. http://books.google.com/?id=T3wWj2kVYZgC&printsec=frontcover.
  7. ↑ R. A. Bailey (2008). Design of comparative experiments. Cambridge University Press. ISBN 978-0-521-68357-9. http://www.cambridge.org/uk/catalogue/catalogue.asp?isbn=9780521683579.
  8. ↑ "Treatment and control groups, In: Wikipedia". San Francisco, California: Wikimedia Foundation, Inc. May 18, 2012. Retrieved 2012-05-31.
  9. ↑ "proof of concept, In: Wiktionary". San Francisco, California: Wikimedia Foundation, Inc. November 10, 2012. Retrieved 2013-01-13.
  10. ↑ Ginger Lehrman and Ian B Hogue, Sarah Palmer, Cheryl Jennings, Celsa A Spina, Ann Wiegand, Alan L Landay, Robert W Coombs, Douglas D Richman, John W Mellors, John M Coffin, Ronald J Bosch, David M Margolis (August 13, 2005). "Depletion of latent HIV-1 infection in vivo: a proof-of-concept study". Lancet 366 (9485): 549-55. doi:10.1016/S0140-6736(05)67098-5. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1894952/. Retrieved 2012-05-09.

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