Mottramite is an

orthorhombic In crystallography, the orthorhombic crystal system is one of the 7 crystal systems. Orthorhombic Lattice (group), lattices result from stretching a cubic crystal system, cubic lattice along two of its orthogonal pairs by two different factors, res ...

anhydrous A substance is anhydrous if it contains no water. Many processes in chemistry can be impeded by the presence of water; therefore, it is important that water-free reagents and techniques are used. In practice, however, it is very difficult to achie ...

vanadate In chemistry, a vanadate is an anionic coordination complex of vanadium. Often vanadate refers to oxoanions of vanadium, most of which exist in its highest oxidation state of +5. The complexes and are referred to as hexacyanovanadate(III) and no ...

hydroxide Hydroxide is a diatomic anion with chemical formula OH−. It consists of an oxygen and hydrogen atom held together by a single covalent bond, and carries a negative electric charge. It is an important but usually minor constituent of water. It ...

mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid substance with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. Rafferty, ed. (2011): Mi ...

, Pb Cu( V O₄)(O H), at the copper end of the

descloizite Descloizite is a rare mineral species consisting of basic lead and zinc vanadium, vanadate, , crystallizing in the orthorhombic crystal system and isomorphous with olivenite. Appreciable gallium and germanium may also be incorporated into the cr ...

subgroup. It was formerly called cuprodescloizite or psittacinite (this mineral characterized in 1868 by

Frederick Augustus Genth Frederick Augustus Ludwig Karl Wilhelm Genth (May 17, 1820 – February 2, 1893) was a German-American chemist, specializing in analytical chemistry and mineralogy. Biography Frederick Augustus Genth was born in Wächtersbach, Hesse-Cassel on M ...

). Duhamelite is a

calcium Calcium is a chemical element; it has symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar to it ...

- and

bismuth Bismuth is a chemical element; it has symbol Bi and atomic number 83. It is a post-transition metal and one of the pnictogens, with chemical properties resembling its lighter group 15 siblings arsenic and antimony. Elemental bismuth occurs nat ...

-bearing variety of mottramite, typically with acicular habit. Mottramite is a member of the adelite-descloizite group. Mottramite, which is a copper rich member, forms a series with descloizite, which is a

zinc Zinc is a chemical element; it has symbol Zn and atomic number 30. It is a slightly brittle metal at room temperature and has a shiny-greyish appearance when oxidation is removed. It is the first element in group 12 (IIB) of the periodic tabl ...

rich member. These two minerals usually contain significant percentages of both copper and zinc and are seldom pure. Mottramite also forms a series with

duftite Duftite is a relatively common arsenate mineral with the formula CuPb(AsO4)(OH), related to conichalcite. It is green and often forms botryoidal aggregates. It is a member of the adelite-descloizite Group, Conichalcite-Duftite Series. Duftite and ...

. It was discovered in 1876 and named for the locality,

Mottram St Andrew Mottram St Andrew is a village and civil parishes in England, civil parish in Cheshire, England. At the 2011 United Kingdom census, 2011 census, it had a population of 493. An affluent village in the Cheshire countryside, it is in the Golden Tria ...

, Cheshire, England, where ore was stockpiled, although it was probably mined from

Pim Hill Pimhill is a geographically large civil parish in Shropshire, England, to the north of Shrewsbury. It is named after a hill, which rises to 163 m, sometimes spelt Pim Hill. In recent times the parish is more well known as "Bomere Heath and Dist ...

Mine, Shrewsbury, Shropshire, England.Kingsbury and Hartley (1956). New occurrences of vanadium minerals (mottramite, descloizite, (discredited) and vanadinite) in the Caldbeck area of Cumberland. Mineralogical Magazine 31:289

Crystallography

Mottramite is an

mineral belonging to the

crystal class In crystallography, a crystallographic point group is a three-dimensional point group whose symmetry operations are compatible with a three-dimensional crystallographic lattice. According to the crystallographic restriction it may only contain on ...

2/m 2/m 2/m, with

space group In mathematics, physics and chemistry, a space group is the symmetry group of a repeating pattern in space, usually in three dimensions. The elements of a space group (its symmetry operations) are the rigid transformations of the pattern that ...

Pnma. The

unit cell In geometry, biology, mineralogy and solid state physics, a unit cell is a repeating unit formed by the vectors spanning the points of a lattice. Despite its suggestive name, the unit cell (unlike a unit vector In mathematics, a unit vector i ...

has sides of lengths a = 7.6 to 7.7 Å, b = 9.2 to 9.5 Å and c = 6.0 to 6.1 Å.Van der Westhuizen, de Bruiyn, Tordiffe and Botha (1986). The descloizite-mottramite series of vanadates from the Otavi Mountain Land, South West Africa: an X-ray study. Mineralogical Magazine 50:137 There are four formula units per unit cell (Z = 4), the

molar mass In chemistry, the molar mass () (sometimes called molecular weight or formula weight, but see related quantities for usage) of a chemical substance ( element or compound) is defined as the ratio between the mass () and the amount of substance ...

is 402.69 g and the calculated

density Density (volumetric mass density or specific mass) is the ratio of a substance's mass to its volume. The symbol most often used for density is ''ρ'' (the lower case Greek letter rho), although the Latin letter ''D'' (or ''d'') can also be u ...

is 6.19 g/cm³. The structure is composed of chains of edge-sharing CuO₆

octahedra In geometry, an octahedron (: octahedra or octahedrons) is any polyhedron with eight faces. One special case is the regular octahedron, a Platonic solid composed of eight equilateral triangles, four of which meet at each vertex. Many types of i ...

and very distorted Pb(O,OH)₈

polyhedra In geometry, a polyhedron (: polyhedra or polyhedrons; ) is a three-dimensional figure with flat polygonal faces, straight edges and sharp corners or vertices. The term "polyhedron" may refer either to a solid figure or to its boundary su ...

linked through VO₄ groups into a tight three-dimensional network.

Appearance

Drusy In geology and mineralogy, druse is a crystal habit represented by the coating of fine crystals on a rock fracture surface, or vein or within a vug or geode. See also * Miarolitic cavity Miarolitic cavities (or miarolitic texture) are typicall ...

crusts of tiny intergrown crystals are common, also encrustations and

mammillary Each vertebra (: vertebrae) is an irregular bone with a complex structure composed of bone and some hyaline cartilage, that make up the vertebral column or spine, of vertebrates. The proportions of the vertebrae differ according to their spinal ...

botryoidal A botryoidal ( ) texture or mineral habit, is one in which the mineral has an external form composed of many rounded segments, named for the Ancient Greek (), meaning "a bunch of grapes".Adjective form: ''botruoeidēs'' This is a common form f ...

surfaces. The crystals are equant dipyramids or prisms parallel to the c

crystal axis In crystallography, crystal structure is a description of ordered arrangement of atoms, ions, or molecules in a crystalline material. Ordered structures occur from intrinsic nature of constituent particles to form symmetric patterns that repeat a ...

, but always microscopic. The colour is various shades of green, yellow-green, blackish brown or nearly black. Crystals often grow step by step, with the different steps or zones having different colours. The streak is yellowish green, or yellow, and the crystals are transparent to opaque, with a greasy lustre. Mottramite-Chrysocolla-247710

Physical properties

cleavage Cleavage may refer to: Science * Cleavage (crystal), the way in which a crystal or mineral tends to split * Cleavage (embryo), the division of cells in an early embryo * Cleavage (geology), foliation of rock perpendicular to stress, a result of ...

has been observed. The mineral is

brittle A material is brittle if, when subjected to stress, it fractures with little elastic deformation and without significant plastic deformation. Brittle materials absorb relatively little energy prior to fracture, even those of high strength. ...

and breaks with a subconchoidal to uneven

fracture Fracture is the appearance of a crack or complete separation of an object or material into two or more pieces under the action of stress (mechanics), stress. The fracture of a solid usually occurs due to the development of certain displacemen ...

. It is quite soft, with

Mohs hardness The Mohs scale ( ) of mineral hardness is a qualitative ordinal scale, from 1 to 10, characterizing scratch resistance of mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid substance with a fair ...

3 to , just a little harder than

calcite Calcite is a Carbonate minerals, carbonate mineral and the most stable Polymorphism (materials science), polymorph of calcium carbonate (CaCO3). It is a very common mineral, particularly as a component of limestone. Calcite defines hardness 3 on ...

. The hardness is slightly greater on crystal surfaces. It is a heavy mineral, with

specific gravity Relative density, also called specific gravity, is a dimensionless quantity defined as the ratio of the density (mass of a unit volume) of a substance to the density of a given reference material. Specific gravity for solids and liquids is nea ...

5.9, because of the

lead Lead () is a chemical element; it has Chemical symbol, symbol Pb (from Latin ) and atomic number 82. It is a Heavy metal (elements), heavy metal that is density, denser than most common materials. Lead is Mohs scale, soft and Ductility, malleabl ...

content. It is readily

soluble In chemistry, solubility is the ability of a substance, the solute, to form a solution with another substance, the solvent. Insolubility is the opposite property, the inability of the solute to form such a solution. The extent of the solubi ...

acids An acid is a molecule or ion capable of either donating a proton (i.e. hydrogen cation, H+), known as a Brønsted–Lowry acid, or forming a covalent bond with an electron pair, known as a Lewis acid. The first category of acids are the ...

Optical properties

Orthorhombic crystals (and

triclinic class=skin-invert-image, 180px, Triclinic (a ≠ b ≠ c ≠ a and α, β, γ, 90° pairwise different) In crystallography, the triclinic (or anorthic) crystal system is one of the seven crystal systems. A crystal system is described by three b ...

and

monoclinic In crystallography, the monoclinic crystal system is one of the seven crystal systems. A crystal system is described by three Vector (geometric), vectors. In the monoclinic system, the crystal is described by vectors of unequal lengths, as in t ...

crystals) have two directions in which light travels with zero

birefringence Birefringence, also called double refraction, is the optical property of a material having a refractive index that depends on the polarization and propagation direction of light. These optically anisotropic materials are described as birefrin ...

; these directions are called the optic axes, and the crystal is said to be biaxial. The speed of a

ray of light ''Ray of Light'' is the seventh studio album by American singer-songwriter Madonna, released on February 22, 1998, by Maverick Records. A major stylistic and aesthetic departure from her previous work, '' Bedtime Stories'', ''Ray of Light'' is ...

travelling through the crystal differs with direction. The direction of the fastest ray is called the X direction and the direction of the slowest ray is called the Z direction. X and Z are

perpendicular In geometry, two geometric objects are perpendicular if they intersect at right angles, i.e. at an angle of 90 degrees or π/2 radians. The condition of perpendicularity may be represented graphically using the '' perpendicular symbol'', � ...

to each other, and a third direction Y is defined as perpendicular to both X and Z; light travelling along Y has an intermediate speed.

Refractive index In optics, the refractive index (or refraction index) of an optical medium is the ratio of the apparent speed of light in the air or vacuum to the speed in the medium. The refractive index determines how much the path of light is bent, or refrac ...

inversely proportional In mathematics, two sequences of numbers, often experimental data, are proportional or directly proportional if their corresponding elements have a constant ratio. The ratio is called ''coefficient of proportionality'' (or ''proportionality ...

to speed, so the refractive indices for the X, Y and Z directions increase from X to Z.Klein and Hurlbut (1993) Manual of Mineralogy 21st Edition. Wiley
For mottramite the orientation with respect to the crystal axes a, b and c is X = c, Y = b and Z = a. The refractive indices are n_α = 2.170(2), n_β = 2.260(2) and n_γ = 2.320(2). The maximum birefringence δ is the difference between the highest and lowest refractive index; for mottramite δ = 0.150. The angle between the two optic axes is called the optic angle, 2V, and it is always acute, and bisected either by X or by Z. If Z is the bisector then the crystal is said to be positive, and if X is the bisector it is said to be negative. Mottramite is usually

biaxial In crystal optics, the index ellipsoid (also known as the optical indicatrix or sometimes as the dielectric ellipsoid) is a geometric construction which concisely represents the refractive indices and associated polarizations ...

(−), and rarely biaxial (+). The measured value of 2V is 73°. Also 2V can be calculated from the values of the refractive indices, giving a value of 46°, which differs considerably from the measured value. 2V depends on the refractive indices, but refractive index varies with

wavelength In physics and mathematics, wavelength or spatial period of a wave or periodic function is the distance over which the wave's shape repeats. In other words, it is the distance between consecutive corresponding points of the same ''phase (waves ...

, and hence with colour. Therefore, 2V also depends on the colour, and is different for red and for violet light. This effect is called dispersion of the optic axes, or just dispersion (not to be confused with

chromatic dispersion Dispersion is the phenomenon in which the phase velocity of a wave depends on its frequency. Sometimes the term chromatic dispersion is used to refer to optics specifically, as opposed to wave propagation in general. A medium having this commo ...

). If 2V is greater for red light than for violet light the dispersion is designated r > v, and vice versa. For mottramite dispersion is strong, usually with r > v, and rarely with r < v. The mineral is

pleochroic Pleochroism is an optical phenomenon in which a substance has different colors when observed at different angles, especially with polarized light. Etymology The roots of the word are from Greek (). It was first made compound in the German term ...

; when viewed along the X or Y direction it appears canary yellow to greenish yellow and when viewed along the Z direction it appears brownish yellow.

Occurrence

The type locality is

, Cheshire, England, UK and

type material In biology, a type is a particular wikt:en:specimen, specimen (or in some cases a group of specimens) of an organism to which the scientific name of that organism is formally associated. In other words, a type is an example that serves to ancho ...

is conserved at the

Natural History Museum, London The Natural History Museum in London is a museum that exhibits a vast range of specimens from various segments of natural history. It is one of three major museums on Exhibition Road in South Kensington, the others being the Science Museum (Lo ...

52314-52315. Mottramite is a secondary,

supergene A supergene is a chromosomal region encompassing multiple neighboring genes that are inherited together because of close genetic linkage, i.e. much less recombination than would normally be expected. This mode of inheritance can be due to genomic ...

mineral found principally in the oxidized zones of

vanadium Vanadium is a chemical element; it has Symbol (chemistry), symbol V and atomic number 23. It is a hard, silvery-grey, malleable transition metal. The elemental metal is rarely found in nature, but once isolated artificially, the formation of an ...

bearing base metal deposits, especially

sandstones Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains, cemented together by another mineral. Sandstones comprise about 20–25% of all sedimentary rocks. Most sandstone is composed o ...

. Associated minerals are

mimetite Mimetite is a lead arsenate chloride mineral () which forms as a secondary mineral in lead deposits, usually by the Redox, oxidation of galena and arsenopyrite. The name derives from the Greek ''mimetes'', meaning "imitator" and refers to mimeti ...

wulfenite Wulfenite is a lead molybdate mineral with the formula Pb Mo O4. It often occurs as thin tabular crystals with a bright orange-red to yellow-orange color, sometimes brown, although the color can be highly variable. In its yellow form it is some ...

cerussite Cerussite (also known as lead carbonate or white lead ore) is a mineral consisting of lead carbonate with the chemical formula PbCO3, and is an important ore of lead. The name is from the Latin ''cerussa'', white lead. ''Cerussa nativa'' was ...

azurite Azurite or '' Azure spar'Krivovichev V. G.'' Mineralogical glossary. Scientific editor A. G. Bulakh. — St.Petersburg: St.Petersburg Univ. Publ. House. 2009. — 556 p. — ISBN 978-5-288-04863-0. ''(in Russian)'' is a soft, deep-blue copp ...

and

dioptase Dioptase is an intense emerald-green to bluish-green mineral that is cyclosilicate of copper. It is transparent to translucent. Its luster is vitreous to sub- adamantine. Its formula is , also reported as . It has a Mohs hardness of 5, the same ...

Localities

Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...

, Kintore open cut: Mottramite is the only

secondary mineral A primary mineral is any mineral formed during the original crystallization of the host Igneous rock, igneous Primary Rock, primary rock and includes the essential mineral(s) used to classify the rock along with any accessory minerals. In ore deposi ...

with essential

recorded from the Kintore open cut,

Broken Hill Broken Hill is a city in the Far West (New South Wales), far west region of outback New South Wales, Australia. An inland mining city, it is near the border with South Australia on the crossing of the Barrier Highway (A32) and the Silver City Hi ...

, Yancowinna County,

New South Wales New South Wales (commonly abbreviated as NSW) is a States and territories of Australia, state on the Eastern states of Australia, east coast of :Australia. It borders Queensland to the north, Victoria (state), Victoria to the south, and South ...

. It has been found scattered on greenish to yellowish drusy plumbogummite – hinsdalite as tiny black glossy pyramids or aggregates of dull black, flattened

bipyramids In geometry, a bipyramid, dipyramid, or double pyramid is a polyhedron formed by fusing two pyramids together base-to-base. The polygonal base of each pyramid must therefore be the same, and unless otherwise specified the base vertices are usu ...

up to 0.4 mm across.Australian Journal of Mineralogy (1997) 3-1:66 * Australia, Braeside Station: Braeside station is in the Gregory Ranges District,

Shire of East Pilbara The Shire of East Pilbara is one of the four local government areas in the Pilbara region of Western Australia. With an area of , larger than the Australian states of Victoria and Tasmania Tasmania (; palawa kani: ''Lutruwita'') is ...

Western Australia Western Australia (WA) is the westernmost state of Australia. It is bounded by the Indian Ocean to the north and west, the Southern Ocean to the south, the Northern Territory to the north-east, and South Australia to the south-east. Western Aust ...

. Both mottramite and

are common in the central part of the Braeside field. They occur with

vanadinite Vanadinite is a mineral belonging to the apatite group of Phosphate minerals, phosphates, with the chemical formula lead, Pb5(vanadium, Voxygen, O4)3chlorine, Cl. It is one of the main industrial ores of the metal vanadium and a minor source of ...

pyromorphite Pyromorphite is a mineral species composed of lead chlorophosphate: Pb5( P O4)3 Cl, sometimes occurring in sufficient abundance to be mined as an ore of lead. Crystals are common, and have the form of a hexagonal prism terminated by the basal p ...

and

. Descloizite-mottramite was the last to crystallise showing a variety of colours and habits. These include yellow-orange drusy or botryoidal opaque crusts on

chalcedony Chalcedony ( or ) is a cryptocrystalline form of silica, composed of very fine intergrowths of quartz and moganite. These are both silica minerals, but they differ in that quartz has a trigonal crystal structure, while moganite is monoclinic ...

, brown, olive or yellow flaky wedge-shaped transparent crystals up to 100

micrometres The micrometre (English in the Commonwealth of Nations, Commonwealth English as used by the International Bureau of Weights and Measures; SI symbol: μm) or micrometer (American English), also commonly known by the non-SI term micron, is a uni ...

wide that form rosettes in association with

coronadite Coronadite is the lead endmember of the coronadite group, a family of tectomanganates with a 2 × 2 tunnel structure. The mineral was named after Francisco Vasquez de Coronado who was an explorer of southwest US. The name was made up by Waldemar ...

and

hemimorphite Hemimorphite is the chemical compound Zinc, Zn4(Pyrosilicate, Si2O7)(Hydroxide, OH)2Water of crystallization, ·H2O, a component of mineral Calamine (mineral), calamine. It is a silicate mineral which, together with smithsonite (ZnCO3), has bee ...

, and short prismatic and

bipyramidal In geometry, a bipyramid, dipyramid, or double pyramid is a polyhedron formed by fusing two pyramids together base-to-base. The polygonal base of each pyramid must therefore be the same, and unless otherwise specified the base vertices are usu ...

green crystals that form a 10 to 15 micrometre thick crust on

quartz Quartz is a hard, crystalline mineral composed of silica (silicon dioxide). The Atom, atoms are linked in a continuous framework of SiO4 silicon–oxygen Tetrahedral molecular geometry, tetrahedra, with each oxygen being shared between two tet ...

.Australian Journal of Mineralogy (2007) 13-2:59 * Australia, Shangri La: At Shangri La, Kununurra, Wyndham-East Kimberley Shire, Western Australia, green to brown mottramite forms thin botryoidal crusts of fine-grained, platy crystals on quartz and iron oxides, and may be associated with vanadinite. Some crusts have a radiating internal texture and show a variation in composition from mottramite at their core, to descloizite at their rim. Mottramite generally grew at the same time as vanadinite.Australian Journal of Mineralogy (2011) 16-1:21–22 * Morocco, Bou Azer: Mottramite is the only vanadium mineral known from the Bou Azer district,

Tazenakht Tazenakht is a village in Errachidia Province, in the Drâa-Tafilalet region in southeastern Morocco Morocco, officially the Kingdom of Morocco, is a country in the Maghreb region of North Africa. It has coastlines on the Mediterranean Se ...

, Ouarzazate Province, Souss-Massa-Draâ Region, Morocco. It has been found as tiny dark brown resinous crystals on a single piece of heavily altered

galena Galena, also called lead glance, is the natural mineral form of lead(II) sulfide (PbS). It is the most important ore of lead and an important source of silver. Galena is one of the most abundant and widely distributed sulfide minerals. It crysta ...

. The specimen shows secondary mineralisation containing

and possibly

.The Mineralogical Record (2007) 38-5:384 * Russia, Berezovskoe Gold Deposit: Mottramite has been found at the Berezovskoe

gold Gold is a chemical element; it has chemical symbol Au (from Latin ) and atomic number 79. In its pure form, it is a brightness, bright, slightly orange-yellow, dense, soft, malleable, and ductile metal. Chemically, gold is a transition metal ...

deposit, Berezovskii, Ekaterinburg, Sverdlovskaya Oblast', in the

Middle Urals The Ural Mountains ( ),; , ; , or simply the Urals, are a mountain range in Eurasia that runs north–south mostly through Russia, from the coast of the Arctic Ocean to the river Ural and northwestern Kazakhstan.tetrahedrite Tetrahedrite is a copper antimony sulfosalt mineral with formula: . It is the antimony endmember of the continuous solid solution series with arsenic-bearing tennantite. Pure endmembers of the series are seldom if ever seen in nature. Of the two, ...

and

tennantite Tennantite is a copper arsenic sulfosalt mineral with an ideal formula . Due to variable substitution of the copper by iron and zinc the formula is . It is gray-black, steel-gray, iron-gray or black in color. A closely related mineral, tetrahed ...

, with associated bushmakinite, cerussite, bindheimite,

vauquelinite Vauquelinite is a complex mineral with the formula Cu Pb2( Cr O4)( PO4)(O H) making it a combined chromate and phosphate of copper and lead. It forms a series with the arsenate mineral fornacite. It was first described in 1818 in the Beryoz ...

and pyromorphite.The Mineralogical Record (2004) 35-2:175 * United Kingdom,

Caldbeck Caldbeck is a village and civil parish in Cumbria, England, historically within Cumberland, it is situated within the Lake District National Park. Part of the parish lies within the Skiddaw Group SSSI (Site of Special Scientific Interest). T ...

Fells: Mottramite occurs at several localities in the Caldbeck Fells, Allerdale, Cumbria, England. * Caldbeck Fells, Arm O'Grain: A variety of supergene minerals occur as microscopic crystals at Arm O'Grain, Caldbeck Fells. These include mimetite, pyromorphite, vanadinite,

, plumbogummite and

beudantite Beudandite is a secondary mineral occurring in the Oxidation, oxidized zones of Polymetal, polymetallic deposits. It is a lead, iron, Arsenate mineral, arsenate, sulfate mineral, sulfate with Chemical formula, endmember formula: PbFe3(OH)6SO4AsO4 ...

, as well as mottramite. Mottramite is the commonest of them. It occurs as black elongated boat shaped crystals up to about one mm long, scattered over white vein quartz. Occasionally, crusts of mottramite occur in cavities in the quartz that appear to have been formed by the dissolution of

baryte Baryte, barite or barytes ( or ) is a mineral consisting of barium sulfate (Ba S O4). Baryte is generally white or colorless, and is the main source of the element barium. The ''baryte group'' consists of baryte, celestine (strontium sulfate), ...

. Mottramite was almost certainly produced by

oxidation Redox ( , , reduction–oxidation or oxidation–reduction) is a type of chemical reaction in which the oxidation states of the reactants change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is ...

of galena.Journal of the Russell Society (2006) 9:44–53 * Caldbeck Fells, Brandy Gill: Mottramite has been reported from Brandy Gill,

Carrock Fell Carrock Fell is a fell in the English Lake District, situated in the northern region of the national park, north-east of Keswick. Etymology The name ''Carrock'' is a Brittonic formation. Sometimes stated as deriving from ''carreg'' meanin ...

, Caldbeck Fells as minute yellowish green globular aggregates associated with

bayldonite Bayldonite (BAIL-done-ite) is a rare secondary mineral with the chemical formula PbCu3(AsO4)2(OH)2. Its provenance has been attributed to Penberthy Croft Mine, Cornwall, England, United Kingdom but there is no substantiating evidence for this and ...

malachite Malachite () is a copper Carbonate mineral, carbonate hydroxide mineral, with the chemical formula, formula Basic copper carbonate, Cu2CO3(OH)2. This opaque, green-banded mineral crystallizes in the monoclinic crystal system, and most often for ...

and mimetite, and as olive-green pyramidal crystals associated with bayldonite, beaverite and beudantite. The primary

sulfide mineral The sulfide minerals are a class of minerals containing sulfide (S2−) or disulfide () as the major anion. Some sulfide minerals are economically important as metal ores. The sulfide class also includes the selenide mineral, selenides, the tell ...

s at Brandy Gill are galena,

chalcopyrite Chalcopyrite ( ) is a copper iron sulfide mineral and the most abundant copper ore mineral. It has the chemical formula CuFeS2 and crystallizes in the tetragonal system. It has a brassy to golden yellow color and a Mohs scale, hardness of 3.5 to 4 ...

and

arsenopyrite Arsenopyrite ( IMA symbol: Apy) is an iron arsenic sulfide (FeAsS). It is a hard ( Mohs 5.5–6) metallic, opaque, steel grey to silver white mineral with a relatively high specific gravity of 6.1. When dissolved in nitric acid, it releases el ...

. * Caldbeck Fells, Short Grain: Mottramite is quite common at Short Grain, Deer Hills, Caldbeck Fells. It usually occurs as thin

druses The Druze ( ; , ' or ', , '), who Endonym and exonym, call themselves al-Muwaḥḥidūn (), are an Arabs, Arab Eastern esotericism, esoteric Religious denomination, religious group from West Asia who adhere to the Druze faith, an Abrahamic ...

of yellow or dark greenish brown crusts associated with pyromorphite or baryte. Less commonly it occurs as

on quartz. The crystals are inconspicuous and rarely exceed 0.1 mm. It is sometimes associated with

chrysocolla Chrysocolla ( ) is a hydrous copper phyllosilicate mineral and mineraloid with the formula (''x'' < 1) or . The structure of the mineral has been questioned, as a 2006 spectrographic study suggest ma ...

. Most mottramite contains some

arsenic Arsenic is a chemical element; it has Symbol (chemistry), symbol As and atomic number 33. It is a metalloid and one of the pnictogens, and therefore shares many properties with its group 15 neighbors phosphorus and antimony. Arsenic is not ...

substituting for vanadium, so there is a gradation toward vanadium-rich duftite.Journal of the Russell Society (2009)12:57 * Caldbeck Fells, Ingray Gill: Minute drusy yellow to yellow-brown mottramite crusts made up of characteristic boat-shaped crystals a few tens of micrometres across cover specimens from the mine dump at Ingray Gill, Caldbeck Fells. Mottramite encrusts mimetite and white to pale green pyromorphite epimorphs after galena. It is one of the most common supergene minerals at Ingray Gill, but because of its colour and habit it is easily mistaken for pyromorphite or mimetite.Journal of the Russell Society (2009) 12:38 * Caldbeck Fells, Low Pike: Several supergene minerals including bayldonite, beudantite,

brochantite Brochantite is a sulfate mineral, one of a number of cupric sulfates. Its chemical formula is Cu4SO4(OH)6. Formed in arid climates or in rapidly oxidizing copper sulfide deposits, it was named by Armand Lévy (mineralogist), Armand Lévy for his ...

, cornwallite, duftite, malachite, mimetite, philipsburgite and pseudomalachite as well as mottramite occur in thin fractures in quartz at

Low Pike Low Pike is a small fell in the England, English Lake District. It has a modest height of 508 m (1,667 ft) and is situated three kilometres north of Ambleside. Low Pike is well seen from the streets of the town as the first prominent f ...

, Caldbeck Fells.Journal of the Russell Society (2003) 8(1):43–44 * Caldbeck Fells, Balliway Rigg: Mottramite is rare at Balliway Rigg. It has been found as minute olive green pyramidal crystals on hemimorphite and chrysocolla and as scattered yellow to yellow-brown blocky crystals on lavender-blue plumbogummite. It also occurs as minute brown pyramidal crystals on green pyromorphite. The largest crystals are a few tenths of a millimetre across.Journal of the Russell Society (2008) 11:19 * Caldbeck Fells, Brae Fell Mine: Mottramite is quite common on the mine dump at

Brae Fell Brae Fell is a fell in the English Lake District, situated north of Keswick it reaches a height of and is regarded as part of the Caldbeck Fells along with High Pike and Carrock Fell even though it has ridge links to the Uldale Fells. It fo ...

Mine, Roughton Gill, Caldbeck Fells, as coatings of minute rice-grain shaped crystals less than 0.1 mm long on quartz. The crystals are dark brown to buff in colour, often associated with pyromorphite, and occasionally associated with cerussite.Journal of the Russell Society (2006) 9:39–44 * Caldbeck Fells, Sandbed Mine: A yellow-brown crust on samples from the dumps of the Sandbed mine has been identified as mottramite.Journal of the Russell Society (2006) 9:2–38 * US, Brown Monster Mine and Reward Mine: Mottramite is relatively common at the Brown Monster Mine and Reward Mine, Russ District,

Inyo County Inyo County () is a county in the eastern central part of the U.S. state of California, located between the Sierra Nevada and the state of Nevada. In the 2020 census, the population was 19,016. The county seat is Independence. Inyo County is ...

California California () is a U.S. state, state in the Western United States that lies on the West Coast of the United States, Pacific Coast. It borders Oregon to the north, Nevada and Arizona to the east, and shares Mexico–United States border, an ...

. It forms pale yellow-green to tan, brick-red and chocolate brown

crusts, commonly associated with mimetite and wulfenite, or with dark reddish-brown vanadinite.The Mineralogical Record (2010) 41-2:189 * US, Otto Mountain: At Otto Mountain,

Baker A baker is a tradesperson who baking, bakes and sometimes Sales, sells breads and other products made of flour by using an oven or other concentrated heat source. The place where a baker works is called a bakery. History Ancient histo ...

San Bernardino County, California San Bernardino County ( ), officially the County of San Bernardino and sometimes abbreviated as S.B. County, is a County (United States), county located in the Southern California, southern portion of the U.S. state of California, and is locat ...

, mottramite is generally seen as crusts of botryoidal green to olive-green spheres in association with white vanadinite needles.Rocks & Minerals (2011) 86-2:132

References

{{Reflist Vanadate minerals Copper(II) minerals Lead minerals Descloizite group Orthorhombic minerals Minerals in space group 62 Minerals described in 1876