Schreyerite (V₂Ti₃O₉), is a vanadium, titanium oxide mineral found in the Lasamba Hill, Kwale district in

Coast Province The Coast Province ( sw, Mkoa wa Pwani) of Kenya, along the Indian Ocean, was one of Kenya's eight provinces. It comprises the Indian Ocean coastal strip with the capital city at Mombasa and was inhabited by the Mijikenda and Swahili, among oth ...

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. It is

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with kyzylkumite. The mineral occurs as exsolution lamellae and particles in

rutile Rutile is an oxide mineral composed of titanium dioxide (TiO2), the most common natural form of TiO2. Rarer Polymorphism (materials science), polymorphs of TiO2 are known, including anatase, akaogiite, and brookite. Rutile has one of the highest ...

, coexisting with

kyanite Kyanite is a typically blue aluminosilicate mineral, found in aluminium-rich metamorphic pegmatites and sedimentary rock. It is the high pressure polymorph of andalusite and sillimanite, and the presence of kyanite in metamorphic rocks gener ...

sillimanite Sillimanite is an aluminosilicate mineral with the chemical formula Al2SiO5. Sillimanite is named after the American chemist Benjamin Silliman (1779–1864). It was first described in 1824 for an occurrence in Chester, Connecticut. Occurrence ...

, and

tourmaline Tourmaline ( ) is a crystalline silicate mineral group in which boron is compounded with elements such as aluminium, iron, magnesium, sodium, lithium, or potassium. Tourmaline is a gemstone and can be found in a wide variety of colors. The ...

in a highly

metamorphosed Metamorphic rocks arise from the transformation of existing rock to new types of rock in a process called metamorphism. The original rock (protolith) is subjected to temperatures greater than and, often, elevated pressure of or more, causi ...

gneiss Gneiss ( ) is a common and widely distributed type of metamorphic rock. It is formed by high-temperature and high-pressure metamorphic processes acting on formations composed of igneous or sedimentary rocks. Gneiss forms at higher temperatures an ...

. It was named after German mineralogist and petrologist Werner Schreyer, for his research on mineralogy of rock-forming minerals and petrology of metamorphic rocks both in nature and by experiment.

Introduction

Investigation of deposits of green vanadium-bearing kornerupine, revealed the presence of a new vanadium mineral through observations in reflected light. Schreyerite was first discovered in the Kwale district, Kenya. Polymorphous with kyzylkumite, it occurs in highly twinned unmixed grains in vanadium-bearing rutile that occurs as idiomorphic crystals in kornerupine-bearing quartz-biotite-sillimanite gneiss. It also occurs in a

pyrite The mineral pyrite (), or iron pyrite, also known as fool's gold, is an iron sulfide with the chemical formula Iron, FeSulfur, S2 (iron (II) disulfide). Pyrite is the most abundant sulfide mineral. Pyrite's metallic Luster (mineralogy), lust ...

deposit at Sartra,

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, in a Pb-Zn ore deposit at

Rampura Agucha Rampura Agucha is a zinc and lead mine located on a massive sulfide deposit in the Bhilwara district of Rajasthan, India. (click on "mines" information) Rampura Agucha is located from Jaipur. It is north of Bhilwara, and northwest of Shahpura ...

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, and recently in

metamorphic rock Metamorphic rocks arise from the transformation of existing rock to new types of rock in a process called metamorphism. The original rock (protolith) is subjected to temperatures greater than and, often, elevated pressure of or more, causin ...

s of the Ol’khon complex on the western shore of

Lake Baikal Lake Baikal (, russian: Oзеро Байкал, Ozero Baykal ); mn, Байгал нуур, Baigal nuur) is a rift lake in Russia. It is situated in southern Siberia, between the federal subjects of Irkutsk Oblast to the northwest and the Repu ...

Russia Russia (, , ), or the Russian Federation, is a List of transcontinental countries, transcontinental country spanning Eastern Europe and North Asia, Northern Asia. It is the List of countries and dependencies by area, largest country in the ...

. Instead of the usual intergrowths with rutile, single crystals of schreyerite were found, associated with

titanite Titanite, or sphene (from the Greek ''sphenos'' (σφηνώ), meaning wedge), is a calcium titanium nesosilicate mineral, Ca Ti Si O5. Trace impurities of iron and aluminium are typically present. Also commonly present are rare earth metals ...

Optical and physical properties

Schreyerite is a reddish-brown, opaque mineral with metallic luster. Its reflectivity is slightly lower than rutile, and as a result, it is mostly gray. Pleochromism is weak: yellowish brown to reddish brown. When immersed in oil, the contrasts between rutile and schreyerite become clearer, and the color becomes more intense. With crossed polarizers, moderate anisotropism becomes evident, so that the very fine lamellar twinning becomes distinct. It has hardness of 7 and calculated specific gravity of 4.46.

References

{{Reflist *Medenbach, O. and K. Schmetzer (1978) Schreyerite, V2Ti3O9, a new mineral. American Mineralogist, Volume 63, pages I182-l186, 1978 *Bernhardt, H.-J., K. Schmetzer, and O. Medenbach (1983) Berdesinskiite, V2TiO5, a new mineral from Kenya and additional data for schreyerite, V2Ti3O9. *Grey, L E. and A. F. Reid (1972) Shear structure compounds (Cr,Fe)2Tin-2O2n-1, derived from the a-PbO2 structural type. J. Solid State. 4, 186-194 *Dobelin N, Reznitsky L Z, Sklyarov E V, Armbruster T, Medenbach OAmerican (2006) Schreyerite, V2Ti3O9: New occurrence and crystal structure. American Mineralogist, (91) 196-202 Oxide minerals Vanadium minerals Titanium minerals Monoclinic minerals Minerals in space group 15 Polymorphism (materials science)