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.

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."[1]

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.[2]

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.

References[edit]

  1. 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. 
  2. Handbook of Mineralogy (PDF).

External links[edit]

{{Geology resources}}