Coloradoite

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Coloradoite
Coloradoite, Pyrite, Quartz-338840.jpg
Coloradoite from the La Plata District of Colorado
General
Category Telluride mineral
Formula
(repeating unit)		HgTe
IMA symbol Clr [1]
Strunz classification 2.CB.05a
Crystal system Cubic
Crystal class Hextetrahedral (43m)
H–M Symbol: (4 3m)
Space group F43m
Unit cell a = 6.453 Å; Z = 4
Identification
ColorIron-black inclining to gray
Crystal habit Massive, granular
Fracture Uneven to subconchordial
Tenacity Brittle
Mohs scale hardness2.5
Luster Bright metallic
Streak Black
Diaphaneity Opaque
Specific gravity 8.10
References [2] [3] [4]

Coloradoite, also known as mercury telluride (HgTe), is a rare telluride ore associated with metallic deposit (especially gold and silver). Gold usually occurs within tellurides, such as coloradoite, as a high-finess native metal. [5]

Contents

The quest for mining led to the discovery of telluride ores which were found to be associated with metals. Tellurides are ingrown into ores containing these precious metals and are also responsible for a significant amount of these metals being produced. Coloradoite, a member of the coordination subclass of tellurides, is a covalent compound that is isostructural with sphalerite (ZnS). [6] Its chemical properties are highly instrumental in distinguishing it from other tellurides. It was first discovered in Colorado in 1877. Since then, other deposits have been found. Although it plays an important role in the geology of minerals, it can also be used for other purposes.

Introduction

Telluride ores occur mainly with metal deposits. In 1848, C.T. Jackson was the first to discover an American mineral containing the element tellurium in the Whitehall mine, in Spotsylvania County, near Fredericksburg, Virginia. [7] Tellurides of gold were first discovered in 1782 in Transylvania and subsequently other telluride ores were found in other parts of the world (Mark and Scibird, 1908). The first discovery and description of coloradoite was by Frederick Augustus Genth in the Boulder veins of Colorado in 1877 [8] and so named after the place of discovery. Other studies have reported its occurrence in other mines of the region and also in mines of the world's significant telluride locations. First classified in the 02 class of minerals by James Dana, [9] its classification number is 02.08.02.05. It is also has a Strunz classification of 02.CB.05a, as a metal sulfide with gold, silver, iron, copper and other metals. [10]

Composition

The chemical formula for coloradoite is HgTe. Theoretically the composition (%) of HgTe is Hg 61.14, Te 38.86; [11] Table 1 shows results from a chemical analyses reported by Vlasov on samples collected from two different locations. Because it is found with other telluride ores, it carries some other metals like gold and silver. [12] In its pure form, it has the composition mentioned above. A little hard to identify, petzite which is hazardous could be mistaken for coloradoite, on the other hand, petzite is anisotropic as opposed to coloradoite being an isotropic mineral. [13] It is a binary compound with the general formula AX.

Table 1. Results of chemical analyses of coloradoite (%) [11]
Components Kalgoorlie, Western Australia Lakeshore, Ontario
Hg60.9561.6258.55
Pb--1.60
Te39.9838.4339.10
Insoluble residue--0.25
Total100.33100.0599.50

Structure

Coloradoite has a sphalerite structure also known as the "diamond" or "blende" structure; a face centered cubic array in which Hg2+ are in tetrahedral coordination with Te2−, with a stacking sequence of ABCABC. [14] The tetrahedra in the sphalerite group are joined through their apices and rotated through 60° with respect to each other. [15] Figure 1 shows the atomic structure of coloradoite. The structure is a unit cube with the Te2− ions at the corners and face centers. The four mercury atoms are coordinated so that each mercury atom lies at the center of a regular tetrahedron of tellurium atoms and each tellurium lies at the center of a regular tetrahedron of mercury atoms. Its crystal point group of 43m and space group is F43m. [2] It is a covalent compound with a high proportion of metallic bonding, due to its low valencies and even lower interatomic distances. It is also isotropic, meaning it has just one refractive index. [6]

Physical properties

Coloradoite is a brittle, massively granular mineral, with a hardness of 2.5. [11] It has a metallic luster, which could be explained by the presence of metallic bonding in the crystal. Its specific gravity is 8.10 and is an opaque mineral with colors iron-black inclining to gray; in polished sections, and white with slight grayish brown tint, tarnishing to dull purple. Its fracture is uneven to subconchordial with a cell length of 6.44 angstroms. [2] For ease of identification, its etching tests are as follows; With HNO3 it slowly produces a weak brown variegated deposit that acts as a protector to the surface and can be removed completely; with aqua regia it effervesces and produces a weak deposit that can be rubbed off and white, radiating spherules are formed, reaction with FeCl3 yields a browning of the surface at different rates and produces black rims of droplet. [13] Reactions with HCl, KCN, KOH and HgCl2 yield no precipitates or residue as opposed to petzite which turns dark brown with HNO3. [13]

Geologic occurrence

Coloradoite was first discovered in 1877 by F. A. Genth, from the Smuggler Mine at Balarat and the Keystone and Mountain Lion mines of the Magnolia district in Colorado; [8] it was named after the state it was found in. Later studies showed its existence in other mines of the region as well as Kalgoorlie, Australia and Kirkland Lake District, Canada. It is found in large quantities in ores made up of intergrown tellurium, calaverite or sylvanite, melonite and altaite, as anhedral grains either enclosed in single crystals of tellurium or localized along grain boundaries in tellurium aggregates, among others. [8] The tectonic settings for ore deposits are; (a) Magmatic deposits (Waarkraal, South Africa) (b) Contact metasomatic (Nickel Plate mine, British Columbia, (c) Lode and Massive replacement deposits (Kirkland Lake, Ontario and South Dakota, respectively), and (d) Cavity filling (Cripple Creek, Colorado, Kalgoorlie, Australia). Tellurides are accountable for just about 20% of gold production and gold mineralization is hosted chiefly by Archean-aged dolerites and basalts that have been metamorphosed to the greenschist facies. This mineralization occurs in hundreds of auriferous and telluride-bearing lodes. [16]

Related Research Articles

<span class="mw-page-title-main">Mineral</span> Crystalline chemical element or compound formed by geologic processes

In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid substance with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.

<span class="mw-page-title-main">Tellurium</span> Chemical element, symbol Te and atomic number 52

Tellurium is a chemical element; it has symbol Te and atomic number 52. It is a brittle, mildly toxic, rare, silver-white metalloid. Tellurium is chemically related to selenium and sulfur, all three of which are chalcogens. It is occasionally found in its native form as elemental crystals. Tellurium is far more common in the Universe as a whole than on Earth. Its extreme rarity in the Earth's crust, comparable to that of platinum, is due partly to its formation of a volatile hydride that caused tellurium to be lost to space as a gas during the hot nebular formation of Earth.

<span class="mw-page-title-main">Sphalerite</span> Zinc-iron sulfide mineral

Sphalerite is a sulfide mineral with the chemical formula (Zn,Fe)S. It is the most important ore of zinc. Sphalerite is found in a variety of deposit types, but it is primarily in sedimentary exhalative, Mississippi-Valley type, and volcanogenic massive sulfide deposits. It is found in association with galena, chalcopyrite, pyrite, calcite, dolomite, quartz, rhodochrosite, and fluorite.

<span class="mw-page-title-main">Petzite</span> Telluride mineral

The mineral petzite, Ag3AuTe2, is a soft, steel-gray telluride mineral generally deposited by hydrothermal activity. It forms isometric crystals, and is usually associated with rare tellurium and gold minerals, often with silver, mercury, and copper.

<span class="mw-page-title-main">Calaverite</span> Telluride of gold

Calaverite, or gold telluride, is an uncommon telluride of gold, a metallic mineral with the chemical formula AuTe2, with approximately 3% of the gold replaced by silver. It was first discovered in Calaveras County, California in 1861, and was named for the county in 1868.

<span class="mw-page-title-main">Sylvanite</span> Silver gold telluride

Sylvanite or silver gold telluride, chemical formula (Ag,Au)Te2, is the most common telluride of gold.

The telluride ion is the anion Te2− and its derivatives. It is analogous to the other chalcogenide anions, the lighter O2−, S2−, and Se2−, and the heavier Po2−.

<span class="mw-page-title-main">Rickardite</span>

Rickardite is a telluride mineral, a copper telluride (Cu7Te5) or Cu3-x (x = 0 to 0.36)Te2. It was first described for an occurrence in the Good Hope Mine, Vulcan district, Gunnison County, Colorado, US, and named for mining engineer Thomas Arthur Rickard (1864–1953). It is a low temperature hydrothermal mineral that occurs associated with vulcanite, native tellurium, cameronite, petzite, sylvanite, berthierite, pyrite, arsenopyrite and bornite.

Weissite is a telluride mineral, a copper telluride. Its chemical formula is Cu
2−xTe. Weissite has hexagonal crystal structure. Its specific gravity is 6 and its Mohs hardness is 3. Occurrence is in Gunnison County, Colorado, Arizona and New Mexico in the United States. It is also reported from Kalgoorlie, Western Australia and Dalarna and Värmland, Sweden.

<span class="mw-page-title-main">Melonite</span>

Melonite is a telluride of nickel; it is a metallic mineral. Its chemical formula is NiTe2. It is opaque and white to reddish-white in color, oxidizing in air to a brown tarnish.

<span class="mw-page-title-main">Telluride mineral</span>

A telluride mineral is a mineral that has the telluride anion as a main component.

<span class="mw-page-title-main">Native metal</span> Form of metal

A native metal is any metal that is found pure in its metallic form in nature. Metals that can be found as native deposits singly or in alloys include aluminium, antimony, arsenic, bismuth, cadmium, chromium, cobalt, indium, iron, manganese, molybdenum, nickel, niobium, rhenium, selenium, tantalum, tellurium, tin, titanium, tungsten, vanadium, and zinc, as well as the gold group and the platinum group. Among the alloys found in native state have been brass, bronze, pewter, German silver, osmiridium, electrum, white gold, silver-mercury amalgam, and gold-mercury amalgam.

<span class="mw-page-title-main">Nagyágite</span> Sulfide mineral

Nagyágite is a rare sulfide mineral with known occurrence associated with gold ores. Nagyágite crystals are opaque, monoclinic and dark grey to black coloured.

<span class="mw-page-title-main">Roscoelite</span> True mica, phyllosilicate mineral

Roscoelite is a green mineral from the mica group that contains vanadium.

<span class="mw-page-title-main">Vulcanite</span>

Vulcanite is a rare copper telluride mineral. The mineral has a metallic luster, and has a green or bronze-yellow tint. It has a hardness between 1 and 2 on the Mohs scale. Its crystal structure is orthorhombic.

Gold chalcogenides are compounds formed between gold and one of the chalcogens, elements from group 16 of the periodic table: oxygen, sulfur, selenium, or tellurium.

<span class="mw-page-title-main">Uytenbogaardtite</span> Sulfide mineral

The mineral uytenbogaardtite, Ag3AuS2, is a soft, greyish white sulfide mineral, occurring in hydrothermal Au-Ag-quartz veins. It occurs as tiny crystals, visible only with a microscope. It has a metallic luster and a hardness on the Mohs scale of 2 (gypsum).

Commoner, Zimbabwe is a populated place and a place where highly deformed and folded quartz reef structure gold ore is extracted. It is about 50 km west-southwest of Kadoma by air and 68 km by road. It is 67 km north-west of Kwekwe by air and 96 km by road. It is in Zhombe Kwekwe District, Midlands Province, Zimbabwe. Commoner is not to be confused with Commoner Gold Mine near Kadoma in Mashonaland West Province.

<span class="mw-page-title-main">Molybdenum ditelluride</span> Chemical compound

Molybdenum(IV) telluride, molybdenum ditelluride or just molybdenum telluride is a compound of molybdenum and tellurium with formula MoTe2, corresponding to a mass percentage of 27.32% molybdenum and 72.68% tellurium.

Telluric silver — is an obsolete trivial name, which miners, geologists and representatives of other applied professions actually applied to several rare ore minerals, tellurides of silver, as well as to chemical compounds of similar composition. It may refer to:

References

  1. ↑ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi: 10.1180/mgm.2021.43 . S2CID   235729616.
  2. 1 2 3 Anthony, John W.; Bideaux, Richard A; Bkadh, Kenneth W. and Nichols, Monte C. (1990) "Coloradoite" in Handbook of Mineralogy. Volume I: Elements, Sulfides, Sulfosalts. Mineral Data Publishing. Tucson, Arizona. p. 105. ISBN   0962209708.
  3. ↑ Coloradoite. Mindat.org
  4. ↑ Coloradoite. Webmineral
  5. ↑ Fadda, S., Fiori, M., Silvana and Grillo, M. (2005). "Chemical variations in tetrahedrite – tennantite minerals from the Furtei epithermal Au deposit, Sardinia, Italy: Mineral zoning and ore fluids evolution" (PDF). Geochemistry, Mineralogy and Petrology. Bulgarian Academy of Sciences. 43: 79–84.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  6. 1 2 Povarennykh, A. S (1972). Crystal Chemical classification of minerals. Vol I, pp. 120–121
  7. ↑ Kemp, J. F. (1989) Geological occurrence and Associates of The Telluride Gold Ores: The Mining Industry, Its Statistics, Technology and Trade in the United States and Other Countries.Vol. 6, p. 296
  8. 1 2 3 Kelly, William C. and Edwin N. Goddard (1969). "Telluride Ores of Boulder County, Colorado". The Geological Society of America Inc. Memoir 109, pp. 79–80
  9. ↑ Dana, E. S. (1904) The System of Mineralogy of James Dwight Dana: 1837–1868; Descriptive Mineralogy. 6th Edition.
  10. ↑ Strunz, H., Nickel H. E. (2009) Strunz mineralogical tables: chemical-structural mineral classification system. 9th Edition.
  11. 1 2 3 Vlasov, K. A. (1966) Geochemistry and Mineralogy of rare Elements and Genetic Types of Their Deposits. Volume II Mineralogy of Rare Elements. Israel Program for Scientific Translation. pp. 740–741
  12. ↑ Wallace, J. P. (1908) A study of Ore Deposits for the Practical Miner with descriptions of Ore Minerals.
  13. 1 2 3 Ramdohr, P. (1980) The Ore minerals and their intergrowths. Second edition. Volume II, Pergamon Press. p. 524. ISBN   0080238017.
  14. ↑ Klein, C., Dutrow, B. (2007) The 23rd Edition of the Manual of Mineral Science (After JD Dana). Wiley, Hoboken
  15. ↑ Stanton, R. L. (1972), Ore petrology: New York, McGraw-Hill
  16. ↑ Shackleton, J. M., G. Spry, P. G., and Bateman, R. (2003). "Telluride Mineralogy of The Golden Mile Deposit, Kalgoorlie, Western Australia". The Canadian Mineralogist. 41 (6): 1503–1524. doi:10.2113/gscanmin.41.6.1503.{{cite journal}}: CS1 maint: multiple names: authors list (link)
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