Minerals/Metals/Heavys

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

Cinnabars
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. 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.

Lorándite
Lorándite can have the formula TlAsS2.

Leads
"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."

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

Miniums
Minium is a lead tetroxide mineral with the chemical formula: Pb2+2Pb4+O4,, 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.

Minium has 42.9 at. % lead.

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

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

Poloniums
α-Po crystallizes in a simple cubic lattice.

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.

"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."

"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."

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.