uvarovite
{{Short description|Chromium-bearing garnet group}}
{{Infobox mineral
| name = Uvarovite
| category = Nesosilicate
| image = Shuiskite, uvarovite 1100.FS2015 1.jpg
| imagesize = 260px
| caption =
| formula = Ca3Cr2Si3O12
| strunz = 9.AD.25
| system = Cubic
| class = Hexoctahedral (m{{overline|3}}m)
H-M symbol: (4/m {{overline|3}} 2/m)
| symmetry = Ia{{overline|3}}d
| unit cell = a = 11.99 Å; Z = 8
| color = Green, emerald-green, green-black
| habit = Euhedral crystals, granular, massive
| twinning =
| cleavage =
| fracture = Uneven, conchoidal
| mohs = 6.5–7.5
| luster = Vitreous
| polish =
| refractive = n = 1.865
| opticalprop = Isotropic
| birefringence =
| dispersion =
| pleochroism =
| fluorescence=
| absorption =
| streak = White
| gravity = 3.77–3.81
| density =
| melt =
| fusibility =
| diagnostic =
| solubility =
| diaphaneity = Transparent, translucent
| other = Fluorescent red in both short and long UV
| references = [http://www.mindat.org/min-4125.html Uvarovite on Mindat.org][http://rruff.info/doclib/hom/uvarovite.pdf Uvarovite in the Handbook of Mineralogy][http://www.webmineral.com/data/Uvarovite.shtml#.Ufj9s9JkzMM Uvarovite data on Webmineral]
}}
File:Uwarowit (granat) - Saranowskiy Mine, Ural, Rosja.jpg
Uvarovite is a chromium-bearing garnet group species with the formula: Ca3Cr2(SiO4)3. It was discovered in 1832 by Germain Henri Hess who named it after Count Sergei Uvarov (1765–1855), a Russian statesman and amateur mineral collector. It is classified in the ugrandite group alongside the other calcium-bearing garnets andradite and grossular.{{cite book|page=174|title=Elements of Optical Mineralogy: an Introduction to Microscopic Petrography – Part II. Descriptions of Minerals|last=Winchell|author-link=Alexander Winchell|first=Alexander N.|edition=3|year=1933|publisher=John Wiley & Sons, Inc.|hdl = 2027/uc1.b3124253|place=New York|section=Garnet Group}}
Uvarovite is the rarest of the common members of the garnet group,{{cite journal|last=Isaacs|first=T.|year=1965|title=A study of uvarovite|journal=Mineralogical Magazine|volume=35|issue=269|pages=38–45|url=http://rruff.info/doclib/MinMag/Volume_35/35-269-38.pdf|doi=10.1180/minmag.1965.035.269.06|bibcode=1965MinM...35...38I}} and is the only consistently green garnet species, with an emerald-green color. It occurs as well-formed fine-sized crystals.
Occurrence
Uvarovite most commonly occurs in solid solution with grossular or andradite, and is generally found associated with serpentinite, chromite, metamorphic limestones, and skarn ore-bodies.
File:garnet.uvarovite.500pix.jpg|Pendant in uvarovite, a rare bright-green garnet. The long dimension is 2 cm (0.8 inch)
The most significant source of uvarovite historically has been a now-closed copper mine at Outokumpu, Finland, from where most museum specimens have been collected.{{cite journal|title=Connoisseur's choice: uvarovite Outokumpu, Finland|year=1998|journal=Rocks & Minerals|volume=72|issue=2|pages=126–128|last=Cook|first=Robert B.|doi=10.1080/00357529809603048}} The uvarovite crystals found in the Outokumpu district are among a wide range of chromium-rich silicate phases found in association with volcanogenic copper-cobalt-zinc sulfide ore deposits which are known to have an unusually high chromium content.{{cite journal|title=The Cr-minerals of Outokumpu—their chemistry and significance|last=Treloar|first=Peter J.|journal=Journal of Petrology|year=1987|volume=28|issue=5|pages=867–886|doi=10.1093/petrology/28.5.867}}
Uvarovite occurrences in the United States are predominantly found in the western portion of the country, including localities in New Mexico, Arizona, and California. In the eastern United States, uvarovite has been confirmed in Lancaster County, Pennsylvania. The mineral has also been reported from eastern Cuba.{{cite journal|title=Uvarovite in podiform chromite: the Moa-Baracoa ophiolitic massif, Cuba|url=https://www.researchgate.net/publication/236109382|pages=679–690|last1=Proenza|first1=Joaquin|last2=Sole|first2=Jesus|last3=Melgarejo|first3=Joan Carles|journal=The Canadian Mineralogist|volume=37|year=1999}} 9 grains of uvarovite occur in a heavy mineral fraction of bulk stream sediment HM-10 collected in Bunker Hill creek, below the historic Bunker Hill gold mine, south of Nelson in British Columbia Canada. Its source is likely near serpentinites and argillaceous limestones within about 450 m upstream of the silt site.{{cite journal|title=Surveys of recovered Visible Gold, scheelite & metallic mineral grains and Heavy Minerals in bulk stream silts 2013–2015 (Part I)|last=Howard|first=W.R.|url=https://aris.empr.gov.bc.ca/ArisReports/36076.PDF|year=2016|journal=BC MEMPR Assessment Report|volume=#36076|pages=338–339}}
Notable localities in Europe besides the Outokumpu site known to bear uvarovite include Røros, Norway; Pitkyaranta, Russia; Val Malenco, Italy; Pico do Posets near Venasque, Spain; Kip Daglari, Turkey; and Biserk and Sarany, Russia. In Africa, uvarovite has been reported from the Bushveld Igneous Complex of Transvaal, South Africa{{cite journal|title=Uvarovite garnet and South African jade (hydrogrossular) from the Bushveld Complex, Transvaal|last=Frankel|first=J. J.|url=https://pubs.geoscienceworld.org/msa/ammin/article-abstract/44/5-6/565/541489|year=1959|journal=American Mineralogist|volume=44|issue=5–6|pages=565–591}} and from the Vumba Schist Belt in Botswana.{{cite journal|title=Occurrence of zoned uvarovite-grossular garnet in a rodingite from the Vumba Schist Belt, Botswana, Africa: implications for the origin of rodingites|url=http://www.minersoc.org/pages/Archive-MM/Volume_58/58-392-375.pdf|last1=Mogessie|first1=A.|last2=Rammlmair|first2=D.|journal=Mineralogical Magazine|volume=58|pages=375–386|year=1994|issue=392|doi=10.1180/minmag.1994.058.392.03|bibcode=1994MinM...58..375M|s2cid=129045367 }} In Asia, uvarovite has been reported from Taiwan.{{cite journal|title=Uvarovite and grossular from the Fengtien nephrite deposits, eastern Taiwan|url=http://rruff.info/doclib/MinMag/Volume_48/48-346-31.pdf|journal=Mineralogical Magazine|volume=48|pages=31–37|year=1984|last1=Wan|first1=Hsien-Ming|last2=Yeh|first2=Chun-Lu|issue=346|doi=10.1180/minmag.1984.048.346.05|bibcode=1984MinM...48...31W|s2cid=140689947 }} and Japan{{cite journal|title=Chrome garnet from the vicinity of Nukabira Mine, Hidaka Province, Hokkaido, Japan|url=https://www.jstage.jst.go.jp/article/pjab1945/45/2/45_2_109/_pdf|last1=Bamba|first1=Takeo|last2=Yagi|first2=Kenzo|last3=Maeda|first3=Kenjiro|journal= Proceedings of the Japan Academy|volume=45|year=1969|issue=2|pages=109–114|doi=10.2183/pjab1945.45.109|doi-access=free}} In Australia, uvarovite has been reported from chromite deposits in southern New South Wales.{{cite journal|title=Chemistry and mineralogy of podiform chromitite deposits, southern NSW, Australia: a guide to their origin and evolution|url=https://www.researchgate.net/publication/226055866|last1=Graham|first1=I. T.|last2=Franklin|first2=B. J.|last3=Marshall|first3=B.|journal=Mineralogy and Petrology|volume=57|pages=129–150|year=1995|issue=3–4|doi=10.1007/bf01162355|s2cid=140631372}}
Properties
Minerals in the uvarovite-grossular series are stable up to temperatures of 1410 °C at low pressure.{{cite journal|title=Uvarovite: stability of uvarovite-grossularite solid solution at low pressure|journal=Contributions to Mineralogy and Petrology|volume=49|pages=211–232|year=1975|last1=Huckenholz|first1=H. G.|last2=Knittel|first2=D.|issue=3|doi=10.1007/bf00376589|bibcode=1975CoMP...49..211H|s2cid=93153558}}
See also
References
{{Reflist}}
External links
{{Commons category|Uvarovite}}