| Uvarovite | |
|---|---|
 | |
| General | |
| Category | Nesosilicate |
| Formula | Ca3Cr2Si3O12 |
| IMA symbol | Uv[1] |
| Strunz classification | 9.AD.25 |
| Crystal system | Cubic |
| Crystal class | Hexoctahedral (m3m) H-M symbol: (4/m3 2/m) |
| Space group | Ia3d |
| Unit cell | a = 11.99 Å; Z = 8 |
| Identification | |
| Color | Green, emerald-green, green-black |
| Crystal habit | Euhedral crystals, granular, massive |
| Fracture | Uneven, conchoidal |
| Mohs scale hardness | 6.5–7.5 |
| Luster | Vitreous |
| Streak | White |
| Diaphaneity | Transparent, translucent |
| Specific gravity | 3.77–3.81 |
| Optical properties | Isotropic |
| Refractive index | n = 1.865 |
| Other characteristics | Fluorescent red in both short and long UV |
| References | [2][3][4] |
_-_Saranowskiy_Mine%2c_Ural%2c_Rosja.jpg)
Uvarovite is achromium-bearinggarnet group species with theformula:Ca3Cr2(SiO4)3. It was discovered in 1832 byGermain Henri Hess who named it after CountSergei Uvarov (1765–1855), aRussian statesman and amateur mineral collector.[2] It is classified in theugrandite group alongside the other calcium-bearing garnetsandradite andgrossular.[5]
Uvarovite is the rarest of the common members of the garnet group,[6] and is the only consistently green garnet species, with an emerald-green color. It occurs as well-formed fine-sized crystals.
Uvarovite most commonly occurs insolid solution withgrossular orandradite, and is generally found associated withserpentinite,chromite, metamorphic limestones, andskarn ore-bodies.[6]
The most significant source of uvarovite historically has been a now-closed copper mine atOutokumpu, Finland, from where most museum specimens have been collected.[7] The uvarovite crystals found in the Outokumpu district are among a wide range of chromium-rich silicate phases found in association withvolcanogenic copper-cobalt-zinc sulfide ore deposits which are known to have an unusually high chromium content.[8]
Uvarovite occurrences in the United States are predominantly found in the western portion of the country, including localities inNew Mexico,Arizona, andCalifornia. In the eastern United States, uvarovite has been confirmed inLancaster County,Pennsylvania.[7] The mineral has also been reported from easternCuba.[9] 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.[10]
Notable localities in Europe besides the Outokumpu site known to bear uvarovite includeRøros, Norway;Pitkyaranta, Russia;Val Malenco, Italy; Pico do Posets nearVenasque, Spain;Kip Daglari, Turkey; andBiserk andSarany, Russia.[7] In Africa, uvarovite has been reported from theBushveld Igneous Complex ofTransvaal,South Africa[11] and from the Vumba Schist Belt inBotswana.[12] In Asia, uvarovite has been reported fromTaiwan[13] andJapan.[14] InAustralia, uvarovite has been reported from chromite deposits in southernNew South Wales.[15]
Minerals in the uvarovite-grossular series are stable up to temperatures of 1410 °C at low pressure.[16]
