Schreyerite
Encyclopedia
Schreyerite is a vanadium, titanium oxide mineral
found in the Lasamba Hill, Kwale district in Coast Province
Kenya
. It is a polymorph
of kyzylkumite.
The mineral occurs as exsolution lamellae and particles in rutile
, coexisting with kyanite
, sillimanite
, and tourmaline
in a highly metamorphosed
gneiss
. 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.
, revealed the presence of a new vanadium mineral through observations in reflected light. Schreyerite was first discovered in the Kwale district, Kenya. A polymorph of 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
deposit at Sartra, Sweden
, in a Pb-Zn ore deposit at Rampura Agucha
, India
, and recently in metamorphic rock
s of the Ol’khon complex on the western shore of Lake Baikal
, Russia
. Instead of the usual intergrowths with rutile, single crystals of schreyerite were found, associated with titanite
.
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.
Oxide mineral
The oxide mineral class includes those minerals in which the oxide anion is bonded to one or more metal ions. The hydroxide bearing minerals are typically included in the oxide class...
found in the Lasamba Hill, Kwale district in Coast Province
Coast Province
Coast Province of Kenya, along the Indian Ocean, is one of Kenya's seven administrative provinces outside Nairobi. It comprises the Indian Ocean coastal strip with the capital city at Mombasa and is inhabited by the Mijikenda and Swahili, among others...
Kenya
Kenya
Kenya , officially known as the Republic of Kenya, is a country in East Africa that lies on the equator, with the Indian Ocean to its south-east...
. It is a polymorph
Polymorphism (materials science)
Polymorphism in materials science is the ability of a solid material to exist in more than one form or crystal structure. Polymorphism can potentially be found in any crystalline material including polymers, minerals, and metals, and is related to allotropy, which refers to chemical elements...
of kyzylkumite.
The mineral occurs as exsolution lamellae and particles in rutile
Rutile
Rutile is a mineral composed primarily of titanium dioxide, TiO2.Rutile is the most common natural form of TiO2. Two rarer polymorphs of TiO2 are known:...
, coexisting with kyanite
Kyanite
Kyanite, whose name derives from the Greek word kuanos sometimes referred to as "kyanos", meaning deep blue, is a typically blue silicate mineral, commonly found in aluminium-rich metamorphic pegmatites and/or sedimentary rock. Kyanite in metamorphic rocks generally indicates pressures higher than...
, sillimanite
Sillimanite
Sillimanite is an alumino-silicate mineral with the chemical formula Al2SiO5. Sillimanite is named after the American chemist Benjamin Silliman . It was first described in 1824 for an occurrence in Chester, Middlesex County, Connecticut, USA....
, and tourmaline
Tourmaline
Tourmaline is a crystal boron silicate mineral compounded with elements such as aluminium, iron, magnesium, sodium, lithium, or potassium. Tourmaline is classified as a semi-precious stone and the gem comes in a wide variety of colors...
in a highly metamorphosed
Metamorphic rock
Metamorphic rock is the transformation of an existing rock type, the protolith, in a process called metamorphism, which means "change in form". The protolith is subjected to heat and pressure causing profound physical and/or chemical change...
gneiss
Gneiss
Gneiss is a common and widely distributed type of rock formed by high-grade regional metamorphic processes from pre-existing formations that were originally either igneous or sedimentary rocks.-Etymology:...
. 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 kornerupineKornerupine
Kornerupine is a rare boro-silicate mineral with the formula 4652. It crystallizes in the orthorhombic - dipyramidal crystal system as brown, green, yellow to colorless slender tourmaline like prisms or in massive fibrous forms. It has a Mohs hardness of 7 and a specific gravity of 3.3 to 3.34...
, revealed the presence of a new vanadium mineral through observations in reflected light. Schreyerite was first discovered in the Kwale district, Kenya. A polymorph of 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
Pyrite
The mineral pyrite, or iron pyrite, is an iron sulfide with the formula FeS2. This mineral's metallic luster and pale-to-normal, brass-yellow hue have earned it the nickname fool's gold because of its resemblance to gold...
deposit at Sartra, Sweden
Sweden
Sweden , officially the Kingdom of Sweden , is a Nordic country on the Scandinavian Peninsula in Northern Europe. Sweden borders with Norway and Finland and is connected to Denmark by a bridge-tunnel across the Öresund....
, in a Pb-Zn ore deposit at Rampura Agucha
Rampura Agucha
Rampura Agucha is a mine of zinc and lead in the Bhilwara district of Rajasthan state of India. It has world's largest deposits of zinc and lead.Hindustan Zinc Limited is owner of this mine.-History:...
, India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...
, and recently in metamorphic rock
Metamorphic rock
Metamorphic rock is the transformation of an existing rock type, the protolith, in a process called metamorphism, which means "change in form". The protolith is subjected to heat and pressure causing profound physical and/or chemical change...
s of the Ol’khon complex on the western shore of Lake Baikal
Lake Baikal
Lake Baikal is the world's oldest at 30 million years old and deepest lake with an average depth of 744.4 metres.Located in the south of the Russian region of Siberia, between Irkutsk Oblast to the northwest and the Buryat Republic to the southeast, it is the most voluminous freshwater lake in the...
, Russia
Russia
Russia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...
. Instead of the usual intergrowths with rutile, single crystals of schreyerite were found, associated with titanite
Titanite
Titanite, or sphene , is a calcium titanium nesosilicate mineral, CaTiSiO5. Trace impurities of iron and aluminium are typically present...
.
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: yellow-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.