Mammothite is a

mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. Rafferty, ed. (2 ...

found in the Mammoth mine in

Tiger The tiger (''Panthera tigris'') is the largest living cat species and a member of the genus ''Panthera''. It is most recognisable for its dark vertical stripes on orange fur with a white underside. An apex predator, it primarily preys on ...

, Arizona and also in

Laurium Laurium or Lavrio ( ell, Λαύριο; grc, Λαύρειον (later ); before early 11th century BC: Θορικός '' Thorikos''; from Middle Ages until 1908: Εργαστήρια ''Ergastiria'') is a town in southeastern part of Attica, Gree ...

, Attika, Greece. This mineral was named in 1985 by Donald R. Peacor, Pete J. Dunn, G. Schnorrer-Köhler, and Richard A. Bideaux, for the Mammoth vein (one of the two main veins in the mine) and the town of Mammoth, Arizona, which was named for the mine. The mammothite that is found in Arizona exist as euhedral crystals imbedded in micro granular, white colored

anglesite Anglesite is a lead sulfate mineral with the chemical formula PbSO4. It occurs as an oxidation product of primary lead sulfide ore, galena. Anglesite occurs as prismatic orthorhombic crystals and earthy masses, and is isomorphous with barite and ...

with a saccharoidal texture. The associated minerals include

phosgenite Phosgenite is a rare mineral consisting of lead chlorocarbonate, (PbCl)2CO3. The tetragonal crystals are prismatic or tabular in habit: they are usually colorless and transparent, and have a brilliant adamantine lustre. Sometimes the crystals ha ...

wulfenite Wulfenite is a lead molybdate mineral with the formula Pb Mo O4. It can be most often found 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 ...

leadhillite Leadhillite is a lead sulfate carbonate hydroxide mineral, often associated with anglesite. It has the formula Pb4SO4(CO3)2(OH)2. Leadhillite crystallises in the monoclinic system, but develops pseudo-hexagonal forms due to crystal twinning. It ...

and

caledonite Caledonite, whose name derives from Caledonia, the historical name of its place of discovery (Scotland), is a richly colored blue-green sulfate-carbonate mineral of lead and copper with an orthorhombic crystal structure. It is an uncommon mineral ...

. In Greece, the mammothite exists as small euhedral crystals and also as microscopic rock cavities lined with projecting crystals within the slags. The associated minerals here are

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

, phosgenite and

matlockite Matlockite is a rare lead halide mineral, named after the town of Matlock in Derbyshire, England, where it was first discovered in a nearby mine. Matlockite (chemical formula: PbFCl) gives its name to the matlockite group which consists of rare ...

. The ideal chemical formula for mammothite is Pb₆ Cu₄ Al Sb⁵⁺ O₂(O H)₁₆ Cl₄(S O₄)₂.

Occurrence

Mammothite is associated with various minerals but different minerals at different locations. In the Mammoth mine in Tiger, Arizona this mineral is associated with phosgenite, wulfenite, leadhillite and caledonite. There are roughly 100 different kinds of mineral species in the Mammoth mine and about 25 of these are considered to be a part of an anomalous oxidized sequence. These minerals will grow in close quarters with each other but other minerals containing Pb, Cu, Fe, and Zn are also present. The minerals contained in this abnormal sequence contain Pb, Cu, SO₄ , and CO₃ and they may occur in the same minerals. The element

Antimony Antimony is a chemical element with the symbol Sb (from la, stibium) and atomic number 51. A lustrous gray metalloid, it is found in nature mainly as the sulfide mineral stibnite (Sb2S3). Antimony compounds have been known since ancient t ...

is a very rare element that is exhibited in mammothite but also in the mineral

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, ...

, which is seen having small crystals that are attached to

pyrite The mineral pyrite (), or iron pyrite, also known as fool's gold, is an iron sulfide with the chemical formula Fe S2 (iron (II) disulfide). Pyrite is the most abundant sulfide mineral. Pyrite's metallic luster and pale brass-yellow hue giv ...

crystals. In Laurium, Attika, Greece, the mammothite exists as small euhedral crystals and also as microscopic rock cavities lined with projecting crystals within the slags. The associated minerals here are cerussite, phosgenite and matlockite.

Physical properties

Mammothite is a cerulean blue to pale blue, transparent mineral with a resinous or subvitreous luster. It exhibits a hardness of 3 on the

Mohs hardness scale The Mohs scale of mineral hardness () is a qualitative ordinal scale, from 1 to 10, characterizing scratch resistance of various minerals through the ability of harder material to scratch softer material. The scale was introduced in 1812 by th ...

. Mammothite occur as tabular to acicular crystals that exhibit radial aggregates. In Arizona, mammothite is mostly tabular but several samples are elongated on the 01axis. In Tiger, Arizona, crystals are less than 1.0 mm in size. The density was difficult to be measured due to the small size and an abundance of other minerals attached to it. By using heavy liquid techniques, it was determined to be greater than 4.2g/cm³ but the idealized end member was calculated to be 5.25g/cm³. In Laurium, Greece, this mineral is different in appearance. The color of the samples may range from pale blue to white. The crystals in Greece are very small and can exhibit two habits. These habits include being prismatic and bladed; or being very prismatic and elongated on the 01axis. Mammothite is brittle and shows distinct cleavage along the plane. The measured density is 5.25 g/cm³.

Optical properties

Mammothite is biaxial positive, which means it will refract light along two axes. It exhibits a 2V_(measured)=80°, strong dispersion with r>v, and displays visible

pleochroism Pleochroism (from Greek πλέων, ''pléōn'', "more" and χρῶμα, ''khrôma'', "color") is an optical phenomenon in which a substance has different colors when observed at different angles, especially with polarized light. Backgrou ...

with varying colors of shades of pale blue. The indices of refraction are α=1.868, β=1.892, γ=1.928. Mammothite is also transparent and does not respond to

ultraviolet radiation Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nm (with a corresponding frequency around 30 PHz) to 400 nm (750 THz), shorter than that of visible light, but longer than X-rays. UV radiation i ...

Chemical properties

The chemical formula for mammothite is Pb₆ Cu₄ Al Sb⁵⁺ O₂(O H)₁₆ Cl₄(S O₄)₂. Mammothite is one of the few minerals that has an Sb atom in the pentavalent state.

Chemical composition

This

microprobe A microprobe is an instrument that applies a stable and well-focused beam of charged particles (electrons or ions) to a sample. Types When the primary beam consists of accelerated electrons, the probe is termed an electron microprobe, when the pri ...

analyses was done on the mammothite from Tiger, Arizona. These crystals were analyzed by using an ARL-SEMQ electron microprobe that used an operating voltage of 15 kV and a sample current of 0.025 µA. The resulted values were then used to get the weight percentages of the sample of mammothite. However, samples of mammothite that were found in Greece were to small to be able to perform this same analyses. The Laurium samples were identified to be mammothite by using the X-ray diffraction method.

X-ray crystallography

Mammothite is in the

monoclinic crystal system In crystallography, the monoclinic crystal system is one of the seven crystal systems. A crystal system is described by three vectors. In the monoclinic system, the crystal is described by vectors of unequal lengths, as in the orthorhombic ...

, with space group C2. The unit cell dimensions are a=18.93(3) Å, b=7.33(1) Å, c=11.35(2) Å, β=112.44(10)°. These values were obtained through

powder diffraction Powder diffraction is a scientific technique using X-ray, neutron, or electron diffraction on powder or microcrystalline samples for structural characterization of materials. An instrument dedicated to performing such powder measurements is call ...

that was found by using a 114.6 mm diameter Gandolfi camera, CuKα X-radiation,

polycrystalline A crystallite is a small or even microscopic crystal which forms, for example, during the cooling of many materials. Crystallites are also referred to as grains. Bacillite is a type of crystallite. It is rodlike with parallel longulites. Stru ...

sample and a silicon sample as an internal standard.

References

{{Authority control Sulfates Monoclinic minerals Minerals in space group 5