Metazeunerite
{{Short description|Arsenate mineral}}
{{Infobox mineral
| name = Metazeunerite
| category = Phosphate minerals
| boxwidth =
| boxbgcolor =
| image = Metazeunerite-Quartz-201156.jpg
| imagesize =
| caption =Metazeunerite crystals to 7 mm on smoky quartz, Erongo Region, Namibia
| formula = Cu(UO2)2(AsO4)2·8H2O
| molweight =
| strunz = 8.EB.10
| system = Tetragonal
| class = Dipyramidal (4/m)
(same H-M symbol)
| symmetry = P4/n
| unit cell = a = 7.1094 Å, c = 17.416 Å;
Z = 2
| color = Varies from pale to green
| habit = Tabular rectangular crystals with two pinacoid faces; foliated or micaceous aggregates
| twinning = Merohedrally twinned
| cleavage = Perfect on {001}; distinct on {010}
| fracture = Uneven
| tenacity = Brittle
| mohs = 2–2.5
| luster = Vitreous to dull
| refractive = nw = 1.643–1.651 nε = 1.623–1.635
| opticalprop = Uniaxial (−)
| birefringence = .020
| pleochroism = Weak
| streak = Pale green
| gravity = 3.87
| density =
| melt =
| fusibility =
|diagnostic =
| solubility = Soluble in acids
| diaphaneity = Transparent to translucent
| other = 25px Radioactive,
Relief: moderate
| references = [https://www.mineralienatlas.de/lexikon/index.php/MineralData?mineral=Metazeunerite Mineralienatlas][http://webmineral.com/data/Metazeunerite.shtml Metazeunerite Mineral Data Webmineral][http://www.mindat.org/min-2698.html Metazeunerite on Mindat]
}}
Metazeunerite is an arsenate mineral with a chemical formula of Cu(UO2)2(AsO4)2·8H2O. The origin of this mineral is almost always from the natural dehydration process of zeunerite.[http://galleries.com/minerals/phosphat/meta-zeu/meta-zeu.htm Amethyst Galleries]
It is named for civil engineer Gustav A. Zeuner, who worked at the School of Mines in Freiberg and its lowered hydration state.
Properties
Its crystal system is tetragonal and its crystal class is 4/m, which is also called the tetragonal-dipyramidal class because it only has a vertical four-fold rotation axis that is perpendicular to the symmetry plane.Roberts, W., Campbell, T., and Rapp, G. (1990) Encyclopedia of Minerals (Second Edition), 558 p. Van Nordstrand Reinhold, New York.Klein, C., and Dutrow, B. (2007) The 23rd Edition of the Manual of Mineral Science (23rd edition), 194 p. John Wiley & Sons, Inc. When looking at a thin section, metzeunerite is anisotropic, meaning that it has pleochroism. When a mineral is anisotropic, one can see whether it is uniaxial or biaxial, depending on how fast the rays of light are moving through the mineral. This mineral is uniaxial negative due to the ordinary ray being slower than the extraordinary ray.[http://www.und.nodak.edu/instruct/mineral/320petrology/opticalmin/birefringence.htm "Optical Properties of Minerals." University of North Dakota]
Occurrence
Metazeunerite is an uncommon radioactive secondary mineral found in "arsenic bearing hydrothermal uranium deposits" across the world.[http://www.handbookofmineralogy.com/pdfs/metazeunerite.pdf "Metazeunerite." Mineral Data Publishing, 2005] This widespread mineral occurs specifically in Europe, western North America, Australia, Brazil and Chile, Namibia, and Kazakhstan. It is currently studied through thermal decomposition by calculating the different levels of dehydration, as zeunerite is transformed into metazeunerite.{{citation|title=Thermal Decomposition of Metazeunerite—a High-resolution Thermogravimetric and Hot-stage Raman Spectroscopic Study|journal=Thermochimica Acta|volume=419|issue=1–2|pages=119–129|doi=10.1016/j.tca.2004.02.006|year=2004|last1=Frost|first1=Ray L|last2=Weier|first2=Matt L|last3=Adebajo|first3=Moses O|s2cid=96215715 |url=https://eprints.qut.edu.au/842/1/46_Thermal_decomposition_meatzeunerite_TCS_Rev2.pdf}} Metazeunerite was shown to be an important solubility limiting phase controlling uranium migration in the soils of the UK's only, and now abandoned, uranium mine, South Terras, located near St Stephen-in-Brannel.{{Cite journal|last1=Corkhill|first1=Claire L.|last2=Crean|first2=Daniel E.|last3=Bailey|first3=Daniel J.|last4=Makepeace|first4=Carmen|last5=Stennett|first5=Martin C.|last6=Tappero|first6=Ryan|last7=Grolimund|first7=Daniel|last8=Hyatt|first8=Neil C.|date=2017-12-14|title=Multi-scale investigation of uranium attenuation by arsenic at an abandoned uranium mine, South Terras|journal=npj Materials Degradation|language=En|volume=1|issue=1|doi=10.1038/s41529-017-0019-9|issn=2397-2106|doi-access=free|url=https://www.dora.lib4ri.ch/psi/islandora/object/psi%3A4595/datastream/PDF/Corkhill-2017-Multi-scale_investigation_of_uranium_attenuation-%28published_version%29.pdf}}
References
{{Reflist}}
Bibliography
- Palache, P.; Berman H.; Frondel, C. (1960). "Dana's System of Mineralogy, Volume II: Halides, Nitrates, Borates, Carbonates, Sulfates, Phosphates, Arsenates, Tungstates, Molybdates, Etc. (Seventh Edition)" John Wiley and Sons, Inc., New York, pp. 993–994.
{{Commons category}}