Tuperssuatsiaite
Encyclopedia
Tuperssuatsiaite is a rare clay mineral found in Greenland
, Namibia
and Brazil
. It is a hydrate
d phyllosilicate (sheet silicate) of sodium
and iron
.
designation IMA1984-002. It was later named after the type locality, Tuperssuatsiat Bay, Ilimaussaq
, Greenland. In 1992 Karup-Moller and Petersen, together with von Knorring and Leonardsen, found more specimens from a second find in the Aris Quarry
in Namibia, that allowed a better definition of the properties and composition of the mineral. Later still, in 2005, more material was found by a group of researchers from the University of São Paulo
at the Bortolan Quarry, Pocos de Caldas
, Brazil, and although the crystals were small, accurate determinations were made of their physical and optical properties, which differed slightly from those of the specimens from Greenland and Namibia.
-sepiolite
group, palygorskite subgroup.
Subgroup members (formulae according to the IMA):
Iron
occurs both in the ferric
state Fe3+ and the ferrous
state Fe2+. The formula for tuperssuatsiaite contains only ferric iron, and the Greenland material is consistent with this. Analysis of the Namibian material, however, shows that part of the iron is in the ferrous state. Manganese
is also present as a substitute for iron, and a zinc
-rich material has been reported from Greenland.
2/m, meaning that it has a twofold axis of rotational symmetry
perpendicular to a mirror plane
. At one time it was thought that the material from Namibia might belong to the monoclinic class 2, without the mirror plane, but a more recent study gives it as 2/m, the same as the material from Greenland.
The space group
is B2/m, meaning that in the unit cell there is one structural unit at each vertex, and one in the centre of each B face. The palygorskite-sepiolite minerals are clay minerals with a layered structure. In tuperssuatsiaite ribbons of SiO4 tetrahedra
, similar to those in the amphibole
structure, are aligned parallel to the c crystal axis
, and they link to form layers parallel to the plane containing the a and b axes. The spacing between the layers, in the c direction, is about 5 Å
, which is typical for minerals with an amphibole-type structure, due to the repeat distance along the chains of tetrahedra. Channels occur that could be occupied by H2O as in palygorskite
.
For the three main localities the reported values are:
. Crystals are transparent with a bright vitreous luster
, but aggregates may be dull and translucent.
(+), with refractive indices
Nx ~ 1.54, Ny ~ 1.56 and Nz ~ 1.58 to 1.60.
For the three main localities the reported values are:
It is mildly pleochroic
, with X colorless, Y colorless to pale brown or green and Z generally reddish brown. No fluorescence
has been observed.
, parallel to the layers within the structure, and twinning
is common.
Fracture
is uneven to conchoidal (shell-like) and the mineral is brittle; it is quite light, with specific gravity
2.465, which is similar to that of quartz
.
is Tuperssuatsiat Bay, Tunugdliarfik Firth (Eriksfjord), Ilimaussaq complex, Narsaq, Kitaa (West Greenland) Province, Greenland, and type material is conserved at the University of Copenhagen
, Copenhagen, Denmark, and at the National Museum of Natural History
, Washington DC, USA, reference number 162402.
Greenland
Greenland is an autonomous country within the Kingdom of Denmark, located between the Arctic and Atlantic Oceans, east of the Canadian Arctic Archipelago. Though physiographically a part of the continent of North America, Greenland has been politically and culturally associated with Europe for...
, Namibia
Namibia
Namibia, officially the Republic of Namibia , is a country in southern Africa whose western border is the Atlantic Ocean. It shares land borders with Angola and Zambia to the north, Botswana to the east and South Africa to the south and east. It gained independence from South Africa on 21 March...
and Brazil
Brazil
Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...
. It is a hydrate
Hydrate
Hydrate is a term used in inorganic chemistry and organic chemistry to indicate that a substance contains water. The chemical state of the water varies widely between hydrates, some of which were so labeled before their chemical structure was understood....
d phyllosilicate (sheet silicate) of sodium
Sodium
Sodium is a chemical element with the symbol Na and atomic number 11. It is a soft, silvery-white, highly reactive metal and is a member of the alkali metals; its only stable isotope is 23Na. It is an abundant element that exists in numerous minerals, most commonly as sodium chloride...
and iron
Iron
Iron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...
.
Discovery
Tuperssuatsiaite was first found by Karup-Moller and Petersen in Greenland, in 1984, and given the International Mineralogical AssociationInternational Mineralogical Association
The International Mineralogical Association is an international group of 38 national societies. The goal is to promote the science of mineralogy and to standardize the nomenclature of the 4000 plus known mineral species...
designation IMA1984-002. It was later named after the type locality, Tuperssuatsiat Bay, Ilimaussaq
Ilimaussaq intrusive complex
The Ilimaussaq intrusive complex is a large alkalic layered intrusion located on the southwest coast of Greenland. It is Mesoproterozoic in age. It is the type locality of agpaitic nepheline syenite and hosts a variety of unusual rock types....
, Greenland. In 1992 Karup-Moller and Petersen, together with von Knorring and Leonardsen, found more specimens from a second find in the Aris Quarry
Windhoek
Windhoek is the capital and largest city of the Republic of Namibia. It is located in central Namibia in the Khomas Highland plateau area, at around above sea level. The 2001 census determined Windhoek's population was 233,529...
in Namibia, that allowed a better definition of the properties and composition of the mineral. Later still, in 2005, more material was found by a group of researchers from the University of São Paulo
University of São Paulo
Universidade de São Paulo is a public university in the Brazilian state of São Paulo. It is the largest Brazilian university and one of the country's most prestigious...
at the Bortolan Quarry, Pocos de Caldas
Poços de Caldas
Poços de Caldas is a city and municipality in south-western Minas Gerais state, Brazil, in the microregion of the same name. Its estimated population in 2009 was 151,449 inhabitants...
, Brazil, and although the crystals were small, accurate determinations were made of their physical and optical properties, which differed slightly from those of the specimens from Greenland and Namibia.
Mineral group
Tuperssuatsiaite is a member of the palygorskitePalygorskite
Palygorskite or attapulgite is a magnesium aluminium phyllosilicate with formula 2Si4O10·4 which occurs in a type of clay soil common to the Southeastern United States. It is one of the types of fuller's earth.-Name:...
-sepiolite
Sepiolite
Sepiolite is a clay mineral, a complex magnesium silicate, a typical formula for which is Mg4Si6O152·6H2O. It can be present in fibrous, fine-particulate, and solid forms....
group, palygorskite subgroup.
Subgroup members (formulae according to the IMA):
- palygorskite (Mg,Al)2Si4O10(OH)·4H2O
- tuperssuatsiaite NaFe3+3Si8O20(OH)2·4H2O
- yofortierite Mn2+5Si8O20(OH)2·8-9H2O
Iron
Iron
Iron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...
occurs both in the ferric
Ferric
Ferric refers to iron-containing materials or compounds. In chemistry the term is reserved for iron with an oxidation number of +3, also denoted iron or Fe3+. On the other hand, ferrous refers to iron with oxidation number of +2, denoted iron or Fe2+...
state Fe3+ and the ferrous
Ferrous
Ferrous , in chemistry, indicates a divalent iron compound , as opposed to ferric, which indicates a trivalent iron compound ....
state Fe2+. The formula for tuperssuatsiaite contains only ferric iron, and the Greenland material is consistent with this. Analysis of the Namibian material, however, shows that part of the iron is in the ferrous state. Manganese
Manganese
Manganese is a chemical element, designated by the symbol Mn. It has the atomic number 25. It is found as a free element in nature , and in many minerals...
is also present as a substitute for iron, and a zinc
Zinc
Zinc , or spelter , is a metallic chemical element; it has the symbol Zn and atomic number 30. It is the first element in group 12 of the periodic table. Zinc is, in some respects, chemically similar to magnesium, because its ion is of similar size and its only common oxidation state is +2...
-rich material has been reported from Greenland.
Structure
The mineral belongs to the monoclinic crystal classMonoclinic crystal system
In crystallography, the monoclinic crystal system is one of the 7 lattice point groups. A crystal system is described by three vectors. In the monoclinic system, the crystal is described by vectors of unequal length, as in the orthorhombic system. They form a rectangular prism with a...
2/m, meaning that it has a twofold axis of rotational symmetry
Rotational symmetry
Generally speaking, an object with rotational symmetry is an object that looks the same after a certain amount of rotation. An object may have more than one rotational symmetry; for instance, if reflections or turning it over are not counted, the triskelion appearing on the Isle of Man's flag has...
perpendicular to a mirror plane
Reflection symmetry
Reflection symmetry, reflectional symmetry, line symmetry, mirror symmetry, mirror-image symmetry, or bilateral symmetry is symmetry with respect to reflection. That is, a figure which does not change upon undergoing a reflection has reflectional symmetry.In 2D there is a line of symmetry, in 3D a...
. At one time it was thought that the material from Namibia might belong to the monoclinic class 2, without the mirror plane, but a more recent study gives it as 2/m, the same as the material from Greenland.
The space group
Space group
In mathematics and geometry, a space group is a symmetry group, usually for three dimensions, that divides space into discrete repeatable domains.In three dimensions, there are 219 unique types, or counted as 230 if chiral copies are considered distinct...
is B2/m, meaning that in the unit cell there is one structural unit at each vertex, and one in the centre of each B face. The palygorskite-sepiolite minerals are clay minerals with a layered structure. In tuperssuatsiaite ribbons of SiO4 tetrahedra
Tetrahedron
In geometry, a tetrahedron is a polyhedron composed of four triangular faces, three of which meet at each vertex. A regular tetrahedron is one in which the four triangles are regular, or "equilateral", and is one of the Platonic solids...
, similar to those in the amphibole
Amphibole
Amphibole is the name of an important group of generally dark-colored rock-forming inosilicate minerals, composed of double chain tetrahedra, linked at the vertices and generally containing ions of iron and/or magnesium in their structures.-Mineralogy:...
structure, are aligned parallel to the c crystal axis
Crystal structure
In mineralogy and crystallography, crystal structure is a unique arrangement of atoms or molecules in a crystalline liquid or solid. A crystal structure is composed of a pattern, a set of atoms arranged in a particular way, and a lattice exhibiting long-range order and symmetry...
, and they link to form layers parallel to the plane containing the a and b axes. The spacing between the layers, in the c direction, is about 5 Å
Ångström
The angstrom or ångström, is a unit of length equal to 1/10,000,000,000 of a meter . Its symbol is the Swedish letter Å....
, which is typical for minerals with an amphibole-type structure, due to the repeat distance along the chains of tetrahedra. Channels occur that could be occupied by H2O as in palygorskite
Palygorskite
Palygorskite or attapulgite is a magnesium aluminium phyllosilicate with formula 2Si4O10·4 which occurs in a type of clay soil common to the Southeastern United States. It is one of the types of fuller's earth.-Name:...
.
Unit cell
There are two formula units per unit cell (Z = 2), and the cell dimensions vary slightly for specimens from different locations; for all specimens, to the nearest Å, a = 14 Å, b = 18 Å and c = 5 Å, and the angle β = 103° to 105°.For the three main localities the reported values are:
- a = 13.729(30) Å, b : 18.000(10) Å, c =4.828(30) Å , β = 104.28(10)° (Greenland)
- a = 13.92(7) Å, b = 17.73(5) Å, c = 5.30(3) Å, β = 104.78(l)° (Namibia)
- a = 13.945 to 14.034 Å, b = 17.841 to 17.93 Å, c = 5.265 to 5.277 Å, β = 103.35 to 103.67° (Brazil)
Appearance
Tuperssuatsiaite occurs as fan-shaped aggregates up to several centimeters across, as rosettes and as fibers elongated parallel to the c axis. It is red-brown in reflected light, and colorless to light yellowish brown in transmitted light, with a brownish yellow streakStreak (mineralogy)
The streak of a mineral is the color of the powder produced when it is dragged across an unweathered surface. Unlike the apparent color of a mineral, which for most minerals can vary considerably, the trail of finely ground powder generally has a more consistent characteristic color, and is thus...
. Crystals are transparent with a bright vitreous luster
Lustre (mineralogy)
Lustre is a description of the way light interacts with the surface of a crystal, rock, or mineral. The word lustre traces its origins back to the Latin word lux, meaning "light", and generally implies radiance, gloss, or brilliance....
, but aggregates may be dull and translucent.
Optical properties
The mineral is biaxialBirefringence
Birefringence, or double refraction, is the decomposition of a ray of light into two rays when it passes through certain anisotropic materials, such as crystals of calcite or boron nitride. The effect was first described by the Danish scientist Rasmus Bartholin in 1669, who saw it in calcite...
(+), with refractive indices
Refractive index
In optics the refractive index or index of refraction of a substance or medium is a measure of the speed of light in that medium. It is expressed as a ratio of the speed of light in vacuum relative to that in the considered medium....
Nx ~ 1.54, Ny ~ 1.56 and Nz ~ 1.58 to 1.60.
For the three main localities the reported values are:
- Nx = 1.54, Ny = 1.56, Nz = 1.58 (Greenland)
- Nx = 1.5388(5), Ny = 1.5596(5) Nz = 1.595( l) (Namibia)
- Nx = 1.548 to 1.556, Ny = 1.560 to 1.565, Nz = 1.648 to 1.662 (Brazil)
It is mildly pleochroic
Pleochroism
Pleochroism is an optical phenomenon in which a substance appears to be different colors when observed at different angles with polarized light.- Background :Anisotropic crystals will have optical properties that vary with the direction of light...
, with X colorless, Y colorless to pale brown or green and Z generally reddish brown. No fluorescence
Fluorescence
Fluorescence is the emission of light by a substance that has absorbed light or other electromagnetic radiation of a different wavelength. It is a form of luminescence. In most cases, emitted light has a longer wavelength, and therefore lower energy, than the absorbed radiation...
has been observed.
Physical properties
Cleavage is good on a plane containing the b and c crystal axesCrystal structure
In mineralogy and crystallography, crystal structure is a unique arrangement of atoms or molecules in a crystalline liquid or solid. A crystal structure is composed of a pattern, a set of atoms arranged in a particular way, and a lattice exhibiting long-range order and symmetry...
, parallel to the layers within the structure, and twinning
Crystal twinning
Crystal twinning occurs when two separate crystals share some of the same crystal lattice points in a symmetrical manner. The result is an intergrowth of two separate crystals in a variety of specific configurations. A twin boundary or composition surface separates the two crystals....
is common.
Fracture
Fracture (mineralogy)
In the field of mineralogy, fracture is a term used to describe the shape and texture of the surface formed when a mineral is fractured. Minerals often have a highly distinctive fracture, making it a principal feature used in their identification....
is uneven to conchoidal (shell-like) and the mineral is brittle; it is quite light, with specific gravity
Specific gravity
Specific gravity is the ratio of the density of a substance to the density of a reference substance. Apparent specific gravity is the ratio of the weight of a volume of the substance to the weight of an equal volume of the reference substance. The reference substance is nearly always water for...
2.465, which is similar to that of quartz
Quartz
Quartz is the second-most-abundant mineral in the Earth's continental crust, after feldspar. It is made up of a continuous framework of SiO4 silicon–oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall formula SiO2. There are many different varieties of quartz,...
.
Type locality
The type localityType locality (geology)
Type locality , also called type area or type locale, is the where a particular rock type, stratigraphic unit, fossil or mineral species is first identified....
is Tuperssuatsiat Bay, Tunugdliarfik Firth (Eriksfjord), Ilimaussaq complex, Narsaq, Kitaa (West Greenland) Province, Greenland, and type material is conserved at the University of Copenhagen
University of Copenhagen
The University of Copenhagen is the oldest and largest university and research institution in Denmark. Founded in 1479, it has more than 37,000 students, the majority of whom are female , and more than 7,000 employees. The university has several campuses located in and around Copenhagen, with the...
, Copenhagen, Denmark, and at the National Museum of Natural History
National Museum of Natural History
The National Museum of Natural History is a natural history museum administered by the Smithsonian Institution, located on the National Mall in Washington, D.C., United States. Admission is free and the museum is open 364 days a year....
, Washington DC, USA, reference number 162402.
Occurrence and associations
- Greenland: The mineral occurs at the type locality in the Ilimaussaq intrusive complexIlimaussaq intrusive complexThe Ilimaussaq intrusive complex is a large alkalic layered intrusion located on the southwest coast of Greenland. It is Mesoproterozoic in age. It is the type locality of agpaitic nepheline syenite and hosts a variety of unusual rock types....
, Greenland, as a cavity filling in late-stage, low-temperature veinsVein (geology)In geology, a vein is a distinct sheetlike body of crystallized minerals within a rock. Veins form when mineral constituents carried by an aqueous solution within the rock mass are deposited through precipitation...
with adularia, natroliteNatroliteNatrolite is a tectosilicate mineral species belonging to the zeolite group. It is a hydrated sodium and aluminium silicate with the formula . The type locality is Hohentwiel, Hegau, Germany....
and aegirineAegirineAegirine is a member of the clinopyroxene group of inosilicates. Aegirine is the sodium endmember of the aegirine-augite series. Aegirine has the chemical formula NaFeSi2O6 in which the iron is present as Fe3+. In the aegirine-augite series the sodium is variably replaced by calcium with iron and...
, and in late natrolite-albiteAlbiteAlbite is a plagioclase feldspar mineral. It is the sodium endmember of the plagioclase solid solution series. As such it represents a plagioclase with less than 10% anorthite content. The pure albite endmember has the formula NaAlSi3O8. It is a tectosilicate. Its color is usually pure white, hence...
bodies. - Namibia: It occurs in miarolitic cavitiesMiarolitic cavitiesMiarolitic cavities are typically crystal lined irregular cavities or vugs most commonly found in granitic pegmatites, but also found in a variety of igneous rocks. The central portions of pegmatites are often miarolitic as the pegmatite dike crystallizes from the outside walls toward the center...
in the Aris phonolitePhonolitePhonolite is a rare igneous, volcanic rock of intermediate composition, with aphanitic to porphyritic texture....
, Windhoek, Namibia, associated with microclineMicroclineMicrocline is an important igneous rock-forming tectosilicate mineral. It is a potassium-rich alkali feldspar. Microcline typically contains minor amounts of sodium. It is common in granite and pegmatites. Microcline forms during slow cooling of orthoclase; it is more stable at lower temperatures...
, aegirineAegirineAegirine is a member of the clinopyroxene group of inosilicates. Aegirine is the sodium endmember of the aegirine-augite series. Aegirine has the chemical formula NaFeSi2O6 in which the iron is present as Fe3+. In the aegirine-augite series the sodium is variably replaced by calcium with iron and...
, natroliteNatroliteNatrolite is a tectosilicate mineral species belonging to the zeolite group. It is a hydrated sodium and aluminium silicate with the formula . The type locality is Hohentwiel, Hegau, Germany....
, eudialyteEudialyteEudialyte, whose name derives from the Greek phrase Εὖ διάλυτος eu dialytos, meaning "well decomposable", is a somewhat rare, red silicate mineral, which forms in alkaline igneous rocks, such as nepheline syenites...
, bastnasiteBastnasiteThe mineral bastnäsite is one of a family of three carbonate-fluoride minerals, which includes bastnäsite- with a formula of CO3F, bastnäsite- with a formula of CO3F, and bastnäsite- with a formula of CO3F. Most bastnäsite is bastnäsite-, and cerium is by far the most common of the rare earths in...
, makatite, villiaumiteVilliaumiteVilliaumite is a rare halide mineral composed of sodium fluoride, NaF. It is very soluble in water and some specimens fluoresce under long and short wave ultraviolet light. It has a Mohs hardness of 2.5 and is usually red, pink, or orange in color...
, titaniteTitaniteTitanite, or sphene , is a calcium titanium nesosilicate mineral, CaTiSiO5. Trace impurities of iron and aluminium are typically present...
, apophylliteApophylliteThe name apophyllite refers to a specific group of phyllosilicates, a class of minerals that also includes the micas. Originally, the group name referred to a specific mineral, but was redefined in 1978 to stand for a class of minerals of similar chemical makeup that comprise a solid solution...
, analcime and aragoniteAragoniteAragonite is a carbonate mineral, one of the two common, naturally occurring, crystal forms of calcium carbonate, CaCO3...
. Aris is a phonolite quarry about 20 km south of WindhoekWindhoekWindhoek is the capital and largest city of the Republic of Namibia. It is located in central Namibia in the Khomas Highland plateau area, at around above sea level. The 2001 census determined Windhoek's population was 233,529...
, Namibia, which is mined for road gravel. Some zones of the phonolite rock contain numerous small cavities a few centimetres in diameter, with well-formed, microscopic crystals of various minerals, including the abundant occurrence of tuperssuatsiaite. - Brazil: Tuperssuatsiaite occurs in the abandoned Bortolan tinguite quarry, Pocos de CaldasPoços de CaldasPoços de Caldas is a city and municipality in south-western Minas Gerais state, Brazil, in the microregion of the same name. Its estimated population in 2009 was 151,449 inhabitants...
, Minas Gerais, Brazil. Tinguite is a dark green intrusive phonolitePhonolitePhonolite is a rare igneous, volcanic rock of intermediate composition, with aphanitic to porphyritic texture....
composed essentially of alkali feldsparAlkali feldsparThe alkali feldspar group are those feldspar minerals rich in the alkali elements like potassium. The alkali feldspars include: anorthoclase, microcline, orthoclase and sanidine....
, nephelineNephelineNepheline, also called nephelite , is a feldspathoid: a silica-undersaturated aluminosilicate, Na3KAl4Si4O16, that occurs in intrusive and volcanic rocks with low silica, and in their associated pegmatites...
and aegirineAegirineAegirine is a member of the clinopyroxene group of inosilicates. Aegirine is the sodium endmember of the aegirine-augite series. Aegirine has the chemical formula NaFeSi2O6 in which the iron is present as Fe3+. In the aegirine-augite series the sodium is variably replaced by calcium with iron and...
. The tuperssuatsiaite occurs in and near miarolitic cavities in the tinguite, as fibers and needles to 4 micrometres thick and 3 mm wide, isolated or more commonly as rosettes, tufts and shapeless aggregates, often associated with pectolitePectolitePectolite is a white to gray mineral, NaCa2Si3O8, sodium calcium inosilicate hydroxide. It crystallizes in the triclinic system typically occurring in radiated or fibrous crystalline masses. It has a Mohs hardness of 4.5 to 5 and a specific gravity of 2.7 to 2.9. The gemstone variety, larimar, is a...
. - Other localities: Tuperssuatsiaite has also been reported from Quebec, Canada and the Lovozero Massif, Russia.