Pseudobrookite

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Pseudobrookite
Pseudobrookite-219124.jpg
Spray of pseudobrookite needles from Topaz Mountain in Utah (size: 2.7 × 2.0 × 1.6 cm)
General
Category Oxide mineral
Formula
(repeating unit)
Fe2TiO5
IMA symbol Pbrk [1]
Strunz classification 4.CB.15
Crystal system Orthorhombic
Crystal class Dipyramidal (mmm)
H-M symbol: (2/m 2/m 2/m)
Space group Bbmm
Unit cell a = 9.81 Å, b = 9.95 Å,
c = 3.73 Å; Z = 8
Identification
ColorDark reddish brown, brownish black, black
Crystal habit Prismatic to needle like, striated
Cleavage Distinct on {010}
Fracture Uneven to subconchoidal
Mohs scale hardness6
Luster Adamantine, greasy, metallic
Streak Brown
Diaphaneity Opaque, transparent in thin splinters
Specific gravity 4.33–4.39
Optical propertiesBiaxial (+)
Refractive index nα = 2.350 nβ = 2.390 nγ = 2.420
Birefringence δ = 0.070
2V angle Measured: 50°
References [2] [3] [4]

Pseudobrookite is an iron titanium oxide mineral with formula: Fe2TiO5 [2] or (Fe3+,Fe2+)2(Ti,Fe2+)O5. [3]

Discovery and occurrence

Pseudobrookite was first described in 1878 for an occurrence in Uroi Hill (Arany Hill), Simeria, Hunedoara County, Romania. The name is from Greek ψευδής, for false, and brookite because of its misleading similar appearance to brookite. [2]

Pseudobrookite forms as pneumatolytic deposition and alteration within titanium-rich volcanic rocks such as andesite, rhyolite or basalt. It may be associated with xenoliths contained in the volcanics. It also commonly occurs in lithophysae. [4]

It occurs associated with hematite, magnetite, bixbyite, ilmenite, enstatite-ferrosilite, tridymite, quartz, sanidine, topaz, spessartine, beryl, mica, cassiterite and apatite. [4]

Occurrences include: [4]

Related Research Articles

<span class="mw-page-title-main">Titanite</span> Nesosilicate mineral

Titanite, or sphene (from Ancient Greek σφηνώ (sphēnṓ) 'wedge'), is a calcium titanium nesosilicate mineral, CaTiSiO5. Trace impurities of iron and aluminium are typically present. Also commonly present are rare earth metals including cerium and yttrium; calcium may be partly replaced by thorium.

<span class="mw-page-title-main">Rutile</span> Oxide mineral composed of titanium dioxide

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

<span class="mw-page-title-main">Bytownite</span> Mineral: intermediate member of a solid solution series (70 to 90 % anorthite and albite)

Bytownite is a calcium rich member of the plagioclase solid solution series of feldspar minerals with composition between anorthite and labradorite. It is usually defined as having between 70 and 90%An. Like others of the series, bytownite forms grey to white triclinic crystals commonly exhibiting the typical plagioclase twinning and associated fine striations.

<span class="mw-page-title-main">Brookite</span>

Brookite is the orthorhombic variant of titanium dioxide (TiO2), which occurs in four known natural polymorphic forms (minerals with the same composition but different structure). The other three of these forms are akaogiite (monoclinic), anatase (tetragonal) and rutile (tetragonal). Brookite is rare compared to anatase and rutile and, like these forms, it exhibits photocatalytic activity. Brookite also has a larger cell volume than either anatase or rutile, with 8 TiO2 groups per unit cell, compared with 4 for anatase and 2 for rutile. Iron (Fe), tantalum (Ta) and niobium (Nb) are common impurities in brookite.

<span class="mw-page-title-main">Sillimanite</span> Nesosilicate mineral

Sillimanite or fibrolite 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.

<span class="mw-page-title-main">Armalcolite</span> Oxide mineral

Armalcolite is a titanium-rich mineral with the chemical formula (Mg,Fe2+)Ti2O5. It was first found at Tranquility Base on the Moon in 1969 during the Apollo 11 mission, and is named for Armstrong, Aldrin and Collins, the three Apollo 11 astronauts. Together with tranquillityite and pyroxferroite, it is one of three new minerals that were discovered on the Moon. Armalcolite was later identified at various locations on Earth and has been synthesized in the laboratory. (Tranquillityite and pyroxferroite were also later found at various locations on Earth). The synthesis requires low pressures, high temperatures and rapid quenching from about 1,000 °C to the ambient temperature. Armalcolite breaks down to a mixture of magnesium-rich ilmenite and rutile at temperatures below 1,000 °C, but the conversion slows down with cooling. Because of this quenching requirement, armalcolite is relatively rare and is usually found in association with ilmenite and rutile, among other minerals.

<span class="mw-page-title-main">Staurolite</span> Reddish brown to black nesosilicate mineral

Staurolite is a reddish brown to black, mostly opaque, nesosilicate mineral with a white streak. It crystallizes in the monoclinic crystal system, has a Mohs hardness of 7 to 7.5 and the chemical formula: Fe2+2Al9O6(SiO4)4(O,OH)2. Magnesium, zinc and manganese substitute in the iron site and trivalent iron can substitute for aluminium.

<span class="mw-page-title-main">Riebeckite</span> Sodium-rich member of the amphibole group of silicate minerals

Riebeckite is a sodium-rich member of the amphibole group of silicate minerals, chemical formula Na2(Fe2+3Fe3+2)Si8O22(OH)2. It forms a solid solution series with magnesioriebeckite. It crystallizes in the monoclinic system, usually as long prismatic crystals showing a diamond-shaped cross section, but also in fibrous, bladed, acicular, columnar, and radiating forms. Its Mohs hardness is 5.0–6.0, and its specific gravity is 3.0–3.4. Cleavage is perfect, two directions in the shape of a diamond; fracture is uneven, splintery. It is often translucent to nearly opaque.

<span class="mw-page-title-main">Trevorite</span> Rare nickel iron oxide mineral

Trevorite is a rare nickel iron oxide mineral belonging to the spinel group. It has the chemical formula NiFe3+2O4. It is a black mineral with the typical spinel properties of crystallising in the cubic system, black streaked, infusible and insoluble in most acids.

<span class="mw-page-title-main">Bixbyite</span> Manganese-iron mixed oxide mineral

Bixbyite is a manganese iron oxide mineral with chemical formula: (Mn,Fe)2O3. The iron/manganese ratio is quite variable and many specimens have almost no iron. It is a metallic dark black with a Mohs hardness of 6.0 – 6.5. It is a somewhat rare mineral sought after by collectors as it typically forms euhedral isometric crystals exhibiting various cubes, octahedra, and dodecahedra.

<span class="mw-page-title-main">Aenigmatite</span> Sapphirine supergroup, single chain inosilicate mineral

Aenigmatite, also known as cossyrite after Cossyra, the ancient name of Pantelleria, is a sodium, iron, titanium inosilicate mineral. The chemical formula is Na2Fe2+5TiSi6O20 and its structure consists of single tetrahedral chains with a repeat unit of four and complex side branches. It forms brown to black triclinic lamellar crystals. It has Mohs hardness of 5.5 to 6 and specific gravity of 3.74 to 3.85. Aenigmatite forms a solid-solution series with wilkinsonite, Na2Fe2+4Fe3+2Si6O20.

<span class="mw-page-title-main">Galaxite</span>

Galaxite, also known as 'mangan-spinel' is an isometric mineral belonging to the spinel group of oxides with the ideal chemical formula Mn2+Al2O4.

<span class="mw-page-title-main">Chlorargyrite</span> Mineral form of silver chloride

Chlorargyrite is the mineral form of silver chloride (AgCl). Chlorargyrite occurs as a secondary mineral phase in the oxidation of silver mineral deposits. It crystallizes in the isometric–hexoctahedral crystal class. Typically massive to columnar in occurrence it also has been found as colorless to variably yellow cubic crystals. The color changes to brown or purple on exposure to light. It is quite soft with a Mohs hardness of 1 to 2 and dense with a specific gravity of 5.55. It is also known as cerargyrite and, when weathered by desert air, as horn silver. Bromian chlorargyrite is also common. Chlorargyrite is water-insoluble.

<span class="mw-page-title-main">Aheylite</span>

Aheylite is a rare phosphate mineral with formula (Fe2+Zn)Al6[(OH)4|(PO4)2]2·4(H2O). It occurs as pale blue to pale green triclinic crystal masses. Aheylite was made the newest member of the turquoise group in 1984 by International Mineralogical Association Commission on New Minerals and Mineral Names.

<span class="mw-page-title-main">Neptunite</span>

Neptunite is a silicate mineral with the formula KNa2Li(Fe2+, Mn2+)2Ti2Si8O24. With increasing manganese it forms a series with mangan-neptunite. Watatsumiite is the variety with vanadium replacing the titanium in the formula.

Schreyerite (V2Ti3O9), is a vanadium, titanium oxide mineral found in the Lasamba Hill, Kwale district in Coast Province, Kenya. It is polymorphous with kyzylkumite.

<span class="mw-page-title-main">Cafarsite</span> Rare calcium iron arsenite mineral

Cafarsite is a rare calcium iron arsenite mineral. Manganese and titanium occur with iron in the formula.

<span class="mw-page-title-main">Stillwellite-(Ce)</span>

Stillwellite-(Ce) is a rare-earth boro-silicate mineral with chemical formula (Ce,La,Ca)BSiO5.

<span class="mw-page-title-main">Amesite</span>

Amesite is a mineral with general formula of Mg2Al2SiO5(OH)4.

<span class="mw-page-title-main">Minnesotaite</span> Iron silicate mineral

Minnesotaite is an iron silicate mineral with formula: (Fe2+,Mg)3Si4O10(OH)2. It crystallizes in the triclinic crystal system and occurs as fine needles and platelets with other silicates. It is isostructural with the pyrophyllite-talc mineral group.

References

  1. Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi: 10.1180/mgm.2021.43 . S2CID   235729616.
  2. 1 2 3 Pseudobrookite on Mindat.org
  3. 1 2 Pseudobrookite on Webmin
  4. 1 2 3 4 Handbook of Mineralogy