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Information about Galena

Galena lanita

Galena crystal from Kansas
General
CategorySulfides
Chemical formulalead sulfide (PbS)
Identification
ColorLead gray, silvery
Crystal habitCubes and octahedra, tabular and sometimes skeletal crystals
Crystal systemIsometric hexoctahedral
CleavageCubic
FractureFlat (when cubic) to even
Mohs Scale hardness2.5 - 2.75
LusterMetallic
Refractive indexOpaque
PleochroismNone
StreakLead gray
Specific gravity7.4 - 7.6
Fusibility2
Enlarge picture
Galena's unit cell


Galena is the natural mineral form of lead sulfide. It is the most important lead ore mineral.

Galena is one of the most abundant and widely distributed sulfide minerals. It crystallizes in the cubic crystal system often showing octahedral forms. It is often associated with the minerals sphalerite, calcite and fluorite.

Lead ore deposits

Galena deposits often contain significant amounts of silver as included silver sulfide mineral phases or as limited solid solution within the galena structure. These argentiferous galenas have long been the most important ore of silver in mining. In addition zinc, cadmium, antimony, arsenic and bismuth also occur in variable amounts in lead ores. Selenium substitutes for sulfur in the structure constituting a solid solution series. The lead telluride mineral altaite has the same crystal structure as galena. Within the weathering or oxidation zone galena alters to anglesite (lead sulfate) or cerussite (lead carbonate).

Enlarge picture
Galena from Poland


Galena deposits are found in Wales, France, Romania, Austria, Belgium, Italy, Spain, Scotland, England, Australia, and Mexico. Noted deposits include those at Freiberg, Saxony; Cornwall, Derbyshire, and Cumberland, England; the Sullivan mine of British Columbia; and Broken Hill, Australia. Galena also occurs at Mount Hermon in Northern Israel. In the United States it occurs most notably in the Mississippi Valley type deposits of the Lead Belt in southeastern Missouri, and in similar environments in Illinois, Iowa and Wisconsin. Galena also was a major mineral of the zinc-lead mines of the tri-state district around Joplin in southwestern Missouri and the adjoining areas of Kansas and Oklahoma. Galena is also an important ore mineral in the silver mining regions of Colorado, Idaho, Utah and Montana. Of the latter, the Coeur d'Alene district of northern Idaho was most prominent.

Galena is the official state mineral of the U. S. states: Missouri and Wisconsin.

Galena uses



One of the earliest uses of galena was as kohl, which in Ancient Egypt, was applied around the eyes to reduce the glare of the desert sun and to repel flies, which were a potential source of disease.[1]

Galena is a semiconductor with a small bandgap of about 0.4 eV which found use in early wireless communication systems. For example, it was used as the crystal in crystal radio sets, in which it was used as a point-contact diode to detect the radio signals. The galena crystal was used with a safety pin or similar sharp wire, and was known as a "cat's whisker". Scientists that were linked to this application are Karl Ferdinand Braun and Sir Jagdish Bose. In modern wireless communication systems, galena detectors have been replaced by more reliable semiconductor devices, however, silicon point-contact microwave detectors still exist in the market.

See also

References

Notes

1. ^ Metropolitan Museum of Art. The Art of Medicine in Ancient Egypt. (New York: The Museum, 2005), p. 10, ISBN 1-58839-170-1

External links

CRYSTAL is a quantum chemistry ab initio program, designed primarily for calculations on crystals (3 dimensions), slabs (2 dimensions) and polymers (1 dimension) using translational symmetry, but it can be used for single molecules.[1] It is written by V.R. Saunders, R.
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State of Kansas

Flag of Kansas Seal
Nickname(s): The Sunflower State
Motto(s): Ad astra per aspera

Official language(s) English[1]

Capital Topeka
Largest city Wichita
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A chemical formula is a concise way of expressing information about the atoms that constitute a particular chemical compound. A chemical formula is also a short way of showing how a chemical reaction occurs.
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2
(Amphoteric oxide)
Electronegativity 2.33 (scale Pauling)
Ionization energies
(more) 1st: 715.6 kJmol−1
2nd: 1450.5 kJmol−1
3rd: 3081.
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The term sulfide (also spelled sulphide, see spelling) refers to several types of chemical compounds containing sulfur in its lowest oxidation number of −2.

Formally, "sulfide" is the dianion, S2−
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habit of crystals.

The many terms used by mineralogists to describe crystal habits are useful in communicating what specimens of a particular mineral often look like. Recognizing numerous habits helps a mineralogist to identify a large number of minerals.
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A crystal system is a category of space groups, which characterize symmetry of structures in three dimensions with translational symmetry in three directions, having a discrete class of point groups.
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The cubic crystal system (or isometric) is a crystal system where the unit cell is in the shape of a cube. This is one of the most common and simplest shapes found in metallic crystals.
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Cleavage, in mineralogy, is the tendency of crystalline materials to split along definite planes, creating smooth surfaces, of which there are several named types:
  • Basal cleavage: cleavage parallel to the base of a crystal, or to the plane of the lateral axes.

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fracture is the (local) separation of a body into two, or more, pieces under the action of stress.

The word fracture is often applied to bones of living creatures, or to crystals or crystalline materials, such as gemstones or metal.
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The Mohs scale of mineral hardness characterizes the scratch resistance of various minerals through the ability of a harder material to scratch a softer material. It was created in 1812 by the German mineralogist Friedrich Mohs and is one of several definitions of hardness in
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For other senses of this word, see lustre.


Lustre (American English: luster) is a description of the way light interacts with the surface of a crystal, rock, or mineral.
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The refractive index (or index of refraction) of a medium is a measure for how much the speed of light (or other waves such as sound waves) is reduced inside the medium. For example, typical glass has a refractive index of 1.
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Please help recruit one or [ improve this article] yourself. See the talk page for details.
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The streak (also called powder color) of a mineral is the color of the powder produced when it is dragged across an unweathered surface. Unlike the apparent color of a mineral, which for most minerals can vary considerably, the trail of finely ground powder generally has a
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Please assist in recruiting an expert or [ improve this article] yourself. See the talk page for details. This article has been tagged since November 2006.
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Fusibility is the ease with which a material will melt. Materials such as solder require a low melting point so that when heat is applied to a joint, the solder will melt before the materials being soldered melt, i.e. high fusibility.
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Lead Sulfide is an ionic compound of Lead and Sulfur, having two possible proportions:
  • Lead(II) Sulfide, the ionic compound containing one Lead atom and one Sulfur atom.
  • Lead(IV) Sulfide, the ionic compound containing one Lead atom and two Sulfur atoms.

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2
(Amphoteric oxide)
Electronegativity 2.33 (scale Pauling)
Ionization energies
(more) 1st: 715.6 kJmol−1
2nd: 1450.5 kJmol−1
3rd: 3081.
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ore is a volume of rock containing components or minerals in a mode of occurrence that renders it valuable for mining. An ore must contain materials that are
  • valuable
  • in concentrations that can be profitably mined, transported, milled, and processed.

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The cubic crystal system (or isometric) is a crystal system where the unit cell is in the shape of a cube. This is one of the most common and simplest shapes found in metallic crystals.
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An octahedron (plural: octahedra) is a polyhedron with eight faces. A regular octahedron is a Platonic solid composed of eight equilateral triangles, four of which meet at each .

The octahedron's symmetry group is Oh, of order 48.
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Sphalerite (ZnS) is a mineral that is the chief ore of zinc. It consists largely of zinc sulfide in crystalline form but almost always contains variable iron. When iron content is high it is an opaque black variety, marmatite ((Zn,Fe)S).
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calcite]] The carbonate mineral, calcite, is a chemical or biochemical calcium carbonate corresponding to the formula CaCO3 and is one of the most widely distributed minerals on the Earth's surface.
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Fluorite (also called fluorspar) is a mineral composed of calcium fluoride, CaF2. It is an isometric mineral with a cubic habit, though octahedral and more complex isometric forms are not uncommon.
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Silver (IPA: /ˈsɪlvə(ɹ)/) is a chemical element with the symbol Ag (Latin: argentum) and atomic number 47.
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Mining is the extraction of valuable minerals or other geological materials from the earth, usually (but not always) from an ore body, vein, or (coal) seam.
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The telluride ion is Te2−. It is the final stable member of the series of dianions O2−, S2−, and Se2−.

Tellurides also describe a class of compounds formally derived from Te2−, i.e.
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Altaite also known as lead telluride is a yellowish white mineral with an isometric crystal structure. Altaite is in the galena group of minerals as it shares many of properties of galena. Altaite has an unusually high density for a light colored mineral.
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Weathering is the decomposition of rocks, soils and their minerals through direct contact with the Earth's atmosphere. Weathering occurs in situ, or "with no movement", and thus should not to be confused with erosion, which involves the movement and disintegration of rocks
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