Carlfriesite
| Carlfriesite | |
|---|---|
 Carlfriesite from Moctezuma Mine, Moctezuma, Municipio de Moctezuma, Sonora, Mexico. Picture width: 2 mm. | |
| General | |
| Category | Tellurate minerals |
| Formula (repeating unit) | CaTe4+2Te6+O8 |
| IMA symbol | Clf[1] |
| Strunz classification | 4.JK.25 |
| Dana classification | 34.5.3.1 |
| Crystal system | Monoclinic |
| Crystal class | Prismatic (2/m) (same H-M symbol) |
| Space group | C2/c |
| Unit cell | a = 12.576, b = 5.662 c = 9.994 [Å], Z = 4 |
| Identification | |
| Color | Bright yellow – buttery yellow |
| Crystal habit | Axe-head shaped crystals, botryoidal crusts or radial crystals. |
| Cleavage | Distinct |
| Tenacity | Brittle |
| Mohs scale hardness | 3.5 |
| Luster | Vitreous |
| Streak | Pale yellow |
| Diaphaneity | Transparent |
| Specific gravity | 6.3 (measured) 5.7 (calculated) |
| Optical properties | Biaxial (−) |
| Birefringence | δ = 0.208 |
| Pleochroism | Weak, shades of yellow |
| 2V angle | 80 |
| Ultraviolet fluorescence | None |
| Solubility | Insoluble |
| References | [1][2][3][2] |
Carlfriesite is a rare tellurium mineral with the formula CaTe4+2Te6+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.[3][4][5] It was previously thought to have the formula H4Ca(TeO3)3, but this was proven to be incorrect.[6] It has no uses beyond being a collector's item.
Occurrence
[edit]Carlfriesite is often found in cavities in hydrothermal gold-tellurium deposits. It is found associated with cerussite, chlorargyrite, argentian gold, cesbronite, calcite, dickite, baryte, bornite, galena, hessite and tlapallite.[5] It was first identified in the Bambollita (La Oriental), Moctezuma, Municipio de Moctezuma, Sonora, Mexico. It is also found in another nearby mine, namely the Moctezuma mine.
Synthesis
[edit]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 aggregates of tiny carlfriesite plates. The material mostly consisted of carlfriesite, but also contained 10–15% paratellurite, as determined by X-ray diffraction.[6]
See also
[edit]References
[edit]- ^ 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.
- ^ Mineralienatlas
- ^ Barthelmy, Dave. "Carlfriesite Mineral Data". www.webmineral.com. Retrieved 2016-09-19.
- ^ "Carlfriesite: Carlfriesite mineral information and data". www.mindat.org. Retrieved 2016-09-19.
- ^ a b "Handbook of mineralogy" (PDF). Retrieved 2016-09-19.
- ^ a b Herta Effenberger; Josef Zemann; Helmut Mayer (1978). "Carlfriesite: crystal structure, revision of chemical formula, and synthesis" (PDF). American Mineralogist. 63. Retrieved 2016-09-19.