Minerals/Metals/Heavys

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Heavy metals are mercury (Hg) through polonium (Po) in the Periodic table: Hg, Tl, Pb, Bi, and Po. This lecture focuses on heavy metal minerals.

Mercuries[edit]

This rock has native mercury on it, from the Socrates Mine, Sonoma County, California. Credit: Dave Dyet.{{free media}}

Def. a naturally occurring, silvery-colored, metallic liquid, composed primarily of the chemical element mercury, is called mercury, or native mercury.

Cinnabars[edit]

Cinnabar is a naturally occurring cochineal-red, towards brownish red and lead-gray, mercury-sulfide mineral. Credit: H. Zell.

Cinnabar or cinnabarite (red mercury(II) sulfide (HgS), native vermilion), is the common ore of mercury. Its color is cochineal-red, towards brownish red and lead-gray. Cinnabar [may be] found in a massive, granular or earthy form and is bright scarlet to brick-red in color.[1] Generally cinnabar occurs as a vein-filling mineral associated with recent volcanic activity and alkaline hot springs. Cinnabar is deposited by epithermal ascending aqueous solutions (those near surface and not too hot) far removed from their igneous source.

Thalliums[edit]

Lorándite[edit]

A slender, gemmy, lorandite crystal is perched atop contrasting calcite. Credit: Robert M. Lavinsky.{{free media}}

Lorándite can have the formula TlAsS2.

Leads[edit]

This is a piece of native lead. Credit: Rob Lavinsky.{{free media}}
A piece of lead, cut through, is silvery for a short time, before the surface oxidizes. Credit: Hi-Res Images of Chemical Elements.{{free media}}

"Diamond cubic structures with lattice parameters around the lattice parameter of silicon exists both in thin lead and tin films, and in massive lead and tin, freshly solidified in vacuum of ≈5 x 10-6 Torr. Experimental evidence for almost identical structures of at least three oxide types is presented, demonstrating that lead and tin behave like silicon not only in the initial stages of crystallization, but also in the initial stages of oxidation."[2]

The piece of native lead on the right shows a relatively sharp, and well-formed cuboctahedron of Lead at the top of the specimen, which is associated with elongated crystals on the base and back.

Its source locality is Långban, Filipstad, Värmland, Sweden.

A fresh surface of high purity lead on the left is silvery in appearance.

Altaites[edit]

Rich silvery veins and flecks are altaite throughout the matrix. Credit: Rob Lavinsky.{{free media}}

Altaite has the chemical formula of PbTe. It has face-centered cubic structure with four formula molecules (Z=4) per unit cell. It is 50 atomic percent lead and 50 at. % tellurium. Crystal habits include cubic and octahedral crystals; but much more commonly found in massive and granular forms.

Clausthalites[edit]

Clausthalite is a rare lead selenide exhibiting scintillating, metallic microcrystals coverind the carbonate matrix. Credit: Rob Lavinsky.{{free media}}

Clausthalite is a lead selenide mineral, with chemical formula PbSe. It is a face-centered mineral with Z = 4 formula units per unit cell.

Galenas[edit]

This piece features a pristine, 3-dimensional, superb galena crystal sitting perfectly atop matrix. Credit: Rob Lavinsky.{{free media}}

Galena in the image on the right is the metallic cuboidal crystal atop a matrix. Galena is PbS, 50 atomic % lead and 50 atomic % sulfur. Each cubic unit cell contains four PbS molecules in a face-centered cubic lattice.

Litharges[edit]

This litharge specimen is from "An der Seilbahn" slag locality, Hüsten, Arnsberg, Sauerland, North Rhine-Westphalia, Germany. Credit: Elmar Lackner, with permission.{{fairuse}}

Litharge is one of the natural mineral forms of lead(II) oxide, PbO. Litharge is a secondary mineral which forms from the oxidation of galena ores. It is a coating and encrustation with internal tetragonal crystal structure. It is dimorphous with the orthorhombic form massicot. Z = 2.

Massicots[edit]

This galena matrix specimen is covered with a mustard-yellow crust of massicot. Credit: Rob Lavinsky.{{free media}}

Massicot is lead (II) oxide mineral with an orthorhombic lattice structure, Z = 4.

Miniums[edit]

Intense red microcrystals or druse is minium coating the matrix. Credit: Rob Lavinsky.{{free media}}

Minium is a lead tetroxide mineral with the chemical formula: Pb2+2Pb4+O4, Pb
3
O
4
, also known as red lead. Minium has a light-to-vivid red and may have brown-to-yellow tints. It typically occurs in scaly-to-earthy masses. It crystallizes in the tetragonal crystal system.[3]

Minium has 42.9 at. % lead.

Plattnerites[edit]

This is a very large cube (3.5 cm across) of galena with a coating of the lead oxide plattnerite on it. Credit: Rob Lavinsky.{{free media}}

Plattnerite is a lead oxide mineral. It is the beta crystalline form (β-PbO2) of lead dioxide. It has a tetragonal structure with Z = 2 formula units.

Scrutinyites[edit]

This Scrutinyite, α-PbO
2
, specimen is from the Snake Pit Mine, Mex-Tex Mine, Bingham, Hansonburg District, Socorro Co., New Mexico, USA. Credit: Maggie Wilson, with written permission.{{fairuse}}

Scrutinyite (α-PbO2) is the alpha form of lead dioxide. The orthorhombic unit cell has Z = 4 chemical formula units.

In the image on the right, the Scrutinyite consists of brown to black micro crystals on quartz.

Bismuths[edit]

A rich small mini of the native element bismuth is from from China. Credit: Robert M. Lavinsky.{{free media}}

Bismuth does occur on Earth as native bismuth exampled on the right.

Bismites[edit]

Bismite, pen is for scale, no locality given, mineral collection of Brigham Young University Department of Geology, Provo, Utah. Credit: Andrew Silver.{{free media}}

Bismite is a bismuth oxide mineral, bismuth trioxide, or Bi2O3.

Poloniums[edit]

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.[4]

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.[5]

"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."[6]

"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."[6]

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.

References[edit]

  1. R. J. King (2002). "Minerals Explained 37: Cinnabar". Geology Today 18 (5): 195–9. doi:10.1046/j.0266-6979.2003.00366.x. 
  2. S.K. Peneva, K.D. Djuneva and E.A. Tsukeva (2 May 1981). "RHEED study of the initial stages of crystallization and oxidation of lead and tin". Journal of Crystal Growth 53 (2): 382-396. doi:10.1016/0022-0248(81)90088-9. http://www.sciencedirect.com/science/article/pii/0022024881900889. Retrieved 2017-12-13. 
  3. Handbook of Mineralogy (PDF).
  4. CST (20 November 2000). "The Simple Cubic Lattice". Washington, DC USA: The Naval Research Laboratory. Retrieved 2015-08-27.
  5. CSTPo (20 November 2000). "The A_i (beta Po) Structure". Washington, DC USA: The Naval Research Laboratory. Retrieved 2015-08-27.
  6. 6.0 6.1 Lorence G. Collins (3 February 1997). "Polonium Halos and Myrmekite in Pegmatite and Granite" (PDF). Northridge, California USA: California State University, Northridge. Retrieved 2015-08-27.

External links[edit]