Carlfriesite is a rare

tellurium Tellurium is a chemical element with the 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 fo ...

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

with the formula Ca Te⁴⁺₂ Te⁶⁺ O₈, or more simplified: CaTe₃O₈. It has a Moh's hardness of 3.5 and it occurs in various shades of yellow, ranging from bright yellow to a light buttery color. It was named after Carl Fries Jr. (1910–1965) from the U.S. Geological Survey and the Geological Institute of the National University,

Mexico City Mexico City ( es, link=no, Ciudad de México, ; abbr.: CDMX; Nahuatl: ''Altepetl Mexico'') is the capital and largest city of Mexico, and the most populous city in North America. One of the world's alpha cities, it is located in the Valley of ...

Mexico Mexico ( Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guate ...

. It was previously thought to have the formula H₄Ca(TeO₃)₃, but this was proven to be incorrect. It has no uses beyond being a collector's item.

Occurrence

Carlfriesite is often found in cavities in hydrothermal

gold Gold is a chemical element with the symbol Au (from la, aurum) and atomic number 79. This makes it one of the higher atomic number elements that occur naturally. It is a bright, slightly orange-yellow, dense, soft, malleable, and ductile ...

-tellurium deposits. It is found associated with

cerussite Cerussite (also known as lead carbonate or white lead ore) is a mineral consisting of lead carbonate (PbCO3), and is an important ore of lead. The name is from the Latin ''cerussa'', white lead. ''Cerussa nativa'' was mentioned by Conrad Gess ...

, chlorargyrite, argentian gold,

cesbronite Cesbronite is a copper-tellurium oxysalt mineral with the chemical formula Cu3Te6+O4(OH)4 (IMA 17-C). It is colored green and its crystals are orthorhombic dipyramidal. Cesbronite is rated 3 on the Mohs Scale. It is named after Fabien Cesbron (bo ...

calcite Calcite is a carbonate mineral and the most stable polymorph of calcium carbonate (CaCO3). It is a very common mineral, particularly as a component of limestone. Calcite defines hardness 3 on the Mohs scale of mineral hardness, based on scra ...

, dickite,

baryte Baryte, barite or barytes ( or ) is a mineral consisting of barium sulfate ( Ba S O4). Baryte is generally white or colorless, and is the main source of the element barium. The ''baryte group'' consists of baryte, celestine (strontium sulfate), ...

, bornite,

galena Galena, also called lead glance, is the natural mineral form of lead(II) sulfide (PbS). It is the most important ore of lead and an important source of silver. Galena is one of the most abundant and widely distributed sulfide minerals. It cry ...

, hessite and tlapallite. It was first identified in the Bambollita (La Oriental), Moctezuma, Municipio de Moctezuma,

Sonora Sonora (), officially Estado Libre y Soberano de Sonora ( en, Free and Sovereign State of Sonora), is one of the 31 states which, along with Mexico City, comprise the Federal Entities of Mexico. The state is divided into 72 municipalities; the ...

. It is also found in another nearby mine, namely the Moctezuma mine.

Synthesis

Carlfriesite was found to be synthesizable by heating a mixture of CaO, Te(OH)₆ and TeO₂ to 150–240°C with water at the vapor pressure of the system. The resulting material was very fine-grained and colorless, consisting of

aggregate Aggregate or aggregates may refer to: Computing and mathematics * collection of objects that are bound together by a root entity, otherwise known as an aggregate root. The aggregate root guarantees the consistency of changes being made within the ...

s of tiny carlfriesite plates. The material mostly consisted of carlfriesite, but also contained 10–15% paratellurite, as determined by X-ray diffraction.

References

{{Selenites, selenates, tellurites, and tellurates Tellurate and selenate minerals Calcium minerals Monoclinic minerals Minerals in space group 15

Occurrence

Synthesis

See also

References