carlfriesite

{{Short description|Tellurium mineral}}

{{Infobox mineral

| name = Carlfriesite

| boxwidth =

| boxbgcolor =

| image = Carlfriesite-78800.jpg

| imagesize = 260

| alt =

| caption = Carlfriesite from Moctezuma Mine, Moctezuma, Municipio de Moctezuma, Sonora, Mexico. Picture width: 2 mm.

| category = Tellurate minerals

| formula = CaTe⁴⁺₂Te⁶⁺O₈

| IMAsymbol = Clf{{Cite journal|last=Warr|first=L.N.|date=2021|title=IMA–CNMNC approved mineral symbols|journal=Mineralogical Magazine|volume=85|issue=3|pages=291–320|doi=10.1180/mgm.2021.43|bibcode=2021MinM...85..291W|s2cid=235729616|doi-access=free}}

| molweight =

| strunz = 4.JK.25

| dana = 34.5.3.1

| system = Monoclinic

| class = Prismatic (2/m)
(same H-M symbol)

| symmetry = C2/c

| unit cell = a = 12.576, b = 5.662
c = 9.994 [Å], Z = 4

| color = Bright yellow – buttery yellow

| colour =

| habit = Axe-head shaped crystals, botryoidal crusts or radial crystals.

| twinning =

| cleavage = Distinct

| fracture =

| tenacity = Brittle

| mohs =3.5

| luster =Vitreous

| streak =Pale yellow

| diaphaneity =Transparent

| gravity =6.3 (measured)

5.7 (calculated)

| density =

| polish =

| opticalprop =Biaxial (−)

| refractive =

| birefringence =δ = 0.208

| pleochroism =Weak, shades of yellow

| 2V =80

| dispersion =

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| fluorescence =None

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| fusibility =

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| solubility =Insoluble

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| references ={{ref|1}}{{ref|2}}{{ref|3}}[https://www.mineralienatlas.de/lexikon/index.php/MineralData?mineral=Carlfriesite Mineralienatlas]

}}

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.{{Cite web|url=http://www.webmineral.com/data/Carlfriesite.shtml#.V9-1Ryh9600|title=Carlfriesite Mineral Data|last=Barthelmy|first=Dave|website=www.webmineral.com|access-date=2016-09-19}}{{Cite web|url=http://www.mindat.org/min-899.html|title=Carlfriesite: Carlfriesite mineral information and data.|website=www.mindat.org|access-date=2016-09-19}}{{Cite web|url=http://www.handbookofmineralogy.org/pdfs/carlfriesite.pdf|title=Handbook of mineralogy|access-date=2016-09-19}} It was previously thought to have the formula H₄Ca(TeO₃)₃, but this was proven to be incorrect.{{Cite journal|author1=Herta Effenberger |author2=Josef Zemann |author3=Helmut Mayer |date=1978|title=Carlfriesite: crystal structure, revision of chemical formula, and synthesis|url=http://www.minsocam.org/ammin/AM63/AM63_847.pdf|journal=American Mineralogist|volume=63|access-date=2016-09-19}} It has no uses beyond being a collector's item.