Levinsonite- (Y)
| Levinsonite- (Y) | |
|---|---|
| General and classification | |
| other names |
IMA 1996-057 |
| chemical formula | (Y, Nd, Ce) Al (SO 4 ) 2 (C 2 O 4 ) • 12H 2 O |
|
Mineral class (and possibly department) |
Organic compounds |
|
System no. to Strunz and to Dana |
10.AB.70 ( 8th edition : IX / A.01) 50.01.09.03 |
| Crystallographic Data | |
| Crystal system | monoclinic |
| Crystal class ; symbol | monoclinic prismatic; 2 / m |
| Space group | P 2 / n (No. 13, position 2) |
| Lattice parameters |
a = 10.289 Å ; b = 9.234 Å; c = 11.015 Å β = 108.50 ° |
| Formula units | Z = 2 |
| Frequent crystal faces | {101}, {010}, { 1 01} |
| Physical Properties | |
| Mohs hardness | not definable |
| Density (g / cm 3 ) | 2.181 (calculated) |
| Cleavage | very perfect after {101} |
| Break ; Tenacity | brittle; uneven |
| colour | colorless, white |
| Line color | colorless (i.e. white) |
| transparency | transparent |
| shine | Glass gloss |
| Crystal optics | |
| Refractive indices |
n α = 1.48 n β = 1.49 n γ = 1.59 |
| Birefringence | δ = 0.11 |
| Optical character | biaxial positive |
| Axis angle | 2V = 7 ° (measured), 46 ° (calculated) |
| Other properties | |
| Chemical behavior | easily soluble in water |
| Special features | rapid decay under the electron beam |
Levinsonite- (Y) is a very rare mineral from the mineral class of " organic compounds ". It crystallizes in the monoclinic crystal system with the chemical formula (Y, Nd, Ce) Al (SO 4 ) 2 (C 2 O 4 ) · 12H 2 O, and is thus chemically seen a crystal water-containing yttrium - aluminum - sulphate - oxalate .
Levinsonite (Y) of the type locality forms prismatic, parallel [101] elongated and {101} flattened crystals up to 1 mm in size with a characteristic morphology, furthermore aggregates of five to ten more or less randomly grown crystals.
The mineral comes from "Alum Cave Bluff", a popular tourist attraction in Great Smoky Mountains National Park, Tennessee, where it is formed from the weathering of a pyrite-containing phyllite . The name can be translated as "Alaunhöhlenteilklippe", but there is no cave here, only the above-mentioned, approx. 30 m high cliff, which forms a 10 m deep overhang, protecting the water-soluble sulfate and oxalate minerals formed here .
Etymology and history
In 1981 T. Dennis Coskren from Columbia / Maryland began investigating mineralization at the "Alum Cave Bluff". These investigations led to the identification of a large number of unusual minerals typical of an evaporation environment. However, some phases could not be characterized initially and were given to the Mineralogical Laboratory at the University of Michigan for identification, where it was found that three of these phases are rare metal and sulfate-containing oxalates. All three were recognized after submission to the International Mineralogical Association (IMA), including the mineral confirmed under the number IMA 1996-057, which was discovered in 2001 by a US research team with Roland C. Rouse , Donald R. Peacor , Eric J. Essene , T. Dennis Coskren and Robert J. Lauf in the American science magazine "Geochimica et Cosmochimica Acta" was described as Levinsonite- (Y).
The mineral was named after Alfred Abraham Levinson (1927–2005), professor of mineralogy at the University of Calgary , to whom the internationally recognized nomenclature of minerals containing rare earth metals and thus the “Levinson Modifier” goes back. The Levinson modifier in Levinsonite- (Y) [the suffix "- (Y)"] indicates the dominant rare earth metal (here: yttrium), as the IMA guidelines require when naming minerals containing rare metals .
The type of material for Levinsonit- (Y) at the University of Michigan , Ann Arbor / Michigan , and the Smithsonian Institution belonging to National Museum of Natural History , Washington, DC , kept.
classification
In the now outdated, but still in use 8th edition of the mineral classification according to Strunz , the levinsonite (Y) belonged to the mineral class of "organic compounds" and there to the department of "salts of organic acids", where together with caoxite , coskrenite (Ce ) , Glushinskit , Humboldtin , Lindbergit , Minguzzit , Moolooit , Natroxalat , Novgorodovait , Oxammit , Stepanovit , Weddellite , Wheatleyite , Whewellit , Zhemchuzhnikovit and Zugshunstit- (Ce) the independent "group of oxalates " with the system no. IX / A.01 formed.
The 9th edition of Strunz's mineral systematics , which has been in effect since 2001 and is used by the International Mineralogical Association (IMA), also assigns the Levinsonite (Y) to the class of "organic compounds" and there in the department of "salts of organic acids" a. However, this division is further subdivided according to the type of salt-forming acid , so that the mineral can be found according to its composition in the sub-division "Oxalates", where it is the only member of the unnamed group 10.AB.70 .
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns Levinsonite- (Y) to the class of "organic minerals" and there in the department of the same name. Here it is with Coskrenit- (Ce) and Zugshunstit- (Ce) in the "Zugshunstit group" with the system no. 50.01.09 within the sub-section “ Salts of organic acids (oxalates) ”.
Chemism
Mean values from microprobe analyzes on Levinsonite (Y) from the “Alum Cave Bluff” led to contents of 5.72% Y 2 O 3 , 0.50% La 2 O 3 , 3.02% Ce 2 O 3 , 0.76 % Pr 2 O 3 , 5.94% Nd 2 O 3 , 3.21% Sm 2 O 3 , 0.54% Eu 2 O 3 , 2.23% Gd 2 O 3 , 1.15% Dy 2 O 3 , 0.29% Er 2 O 3 , 7.83% Al 2 O 3 , 24.58% SO 3 , [11.05]% C 2 O 3 and [33.18]% H 2 O (the last two were calculated from the stoichiometry). This resulted in the empirical formula (Y 0.33 Nd 0.23 Ce 0.12 Sm 0.12 Gd 0.08 Dy 0.04 Pr 0.03 La 0.02 Eu 0.02 Er 0.01 ) Σ = 1.00 Al 1.00 (SO 4 ) 2.00 (C 2.00 O 4 ) 12.00H 2 O, converting to (Y, Nd, Ce) Al (SO 4 ) 2 (C 2 O 4 ) · 12H 2 O has been simplified.
Levinsonite- (Y) is the yttrium-dominant analogue of cer-dominated Zugshunstit- (Ce), both of which occur side by side in the “Alum Cave Bluff”. The rare earth metals exhibit strong fractionation between these two minerals. The light rare earth metals (English: "Light Rare Earth Elements", LREE) cerium and praseodymium are concentrated in Zugshunstit- (Ce), neodymium is contained in both oxalates, while yttrium and the medium to heavy rare earth metals ("Medium Rare Earth Elements") and "Heavy Rare Earth Elements", MREE and HREE) Samarium , Europium , Gadolinium , Dysprosium and Erbium are bound to Levinsonite- (Y).
Crystal structure
Levinsonite- (Y) crystallizes monoclinically in the space group P 2 / n (space group no. 13, position 2) with the lattice parameters a = 10.289 Å ; b = 9.234 Å; c = 11.015 Å and β = 108.50 ° as well as two formula units per unit cell .
The structure of Levinsonite (Y) is based on a basic building block, namely chains of alternating REE polyhedra and oxalate groups, one oxalate group having edges in common with the neighboring polyhedra. The basic building block is completed by two sulfate tetrahedra , each of which shares a corner with the REE polyhedron. The REE polyhedron in Zugshunstit- (Ce) is a [8] fold-coordinated, i. H. Eight liganded antiprism with a square cross-section resembling the polyhedra in xenotime. The Al octahedra unusually have only H 2 O ligands of the form Al (H 2 O) 6 , and none of them are linked to any other polyhedron of the structure. These are isolated units that are only linked to the basic building blocks via hydrogen bonds .
properties
morphology
Levinsonite- (Y) forms prismatic and pseudoorthorhombic, parallel [101] elongated and {101} flattened crystals up to 1 mm in size with diagonal stripes . The crystal costume consists of the lateral pinacoid {010} and two pinacoids parallel to the b-axis, {101} and { 1 01}. A different training shows slightly elongated tablets with a rectangular cross-section. Typically five to ten more or less randomly grown crystals come together to form aggregates.
physical and chemical properties
Levinsonite (Y) crystals are colorless or white. Their line color is indicated as colorless. Since the line color corresponds to the powder color and the mineral powder cannot be colorless, the color of the line should best be described as white. The surfaces of the transparent crystals show a clear glass-like sheen .
The mineral shows a very perfect cleavage according to {101}, but breaks due to its brittleness similar to amblygonite , whereby the fracture surfaces are uneven. Because of the small crystal size, neither its Mohs hardness nor Vickers hardness could be determined. Measured values for the density of Levinsonite- (Y) do not exist, the calculated density for the mineral is 2.181 g / cm³.
Levinsonite- (Y) is easily soluble in water without leaving any residue.
Education and Locations
As a very rare mineral formation, Levinsonite- (Y) could only be described from one source so far (as of 2016). Its type locality is the rocky cliff of the "Alum Cave Bluff" in the Great Smoky Mountains National Park, Sevier County , Tennessee , United States . Accompanying minerals are Zugshunstite- (Ce), Coskrenit- (Ce), Epsomite and the “hair salt” Halotrichite , whereby Levinsonite (Y) occurs either embedded in Epsomite and / or Halotrichite or forms free-standing crystals in cavities in these minerals.
Levinsonite- (Y) is a typical secondary formation that occurs in the soils of the “Alum Cave Bluff”. The name of the location is misleading as it is not a cave but a steep, overhanging rock cliff. The cliff and the surrounding rock form part of the Precambrian Anakeesta Formation, a metapelite with the texture of a phyllite, the main minerals of which are muscovite , biotite , chlorite , quartz and pyrite. This area is extremely rainy with rainfall of 2000 mm per year. The resulting weathering of the rock on the cliff also includes the oxidation of the pyrite and the dissolution of the main rock-forming silicates . This, in turn, leads to sulfate-rich solutions with low pH values that are rich in elements from the dissolved silicates such as iron , magnesium , aluminum , potassium , sodium , calcium and manganese . The rare earth metals probably come from altered phases such as monazite and xenotime . When these solutions drip down the walls of the cliff, they get under the sloping surface of the rock overhang, where partial evaporation leads to the precipitation of sulphates, especially those of iron. Most of the water then continues to the bottom at the base of the cliff, where complete evaporation causes the creation of a wide variety of minerals, mainly hydrated and / or hydrated sulfates. These precipitates consist mainly of epsomite and members of the hair salt family, among which apjohnite is the most common mineral.
use
Levinsonite- (Y) is only of interest to mineral collectors due to its rarity.
See also
literature
- Levinsonite- (Y). In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America. 2001 ( PDF, 68 kB )
- Joseph A. Mandarino: New Minerals . In: The Canadian Mineralogist . tape 39 , 2001, p. 1502 , doi : 10.2113 / gscanmin.39.5.1473 ( rruff.info [PDF; 412 kB ]).
- Roland C. Rouse, Donald R. Peacor, Eric J. Essene, T. Dennis Coskren, Robert J. Lauf: The new minerals levinsonite- (Y) [(Y, Nd, Ce) Al (SO 4 ) 2 (C 2 O 4 ) · 12H 2 O] and zugshunstite- (Ce) [(Ce, Nd, La) Al (SO 4 ) 2 (C 2 O 4 ) · 12H 2 O]: Coexisting oxalates with different structures and differentiation of LREE and HREE . In: Geochimica et Cosmochimica Acta . tape 65 , 2001, p. 1101–1115 , doi : 10.1016 / S0016-7037 (00) 00568-8 .
Web links
- Mineral Atlas: Levinsonite- (Y) (Wiki)
- Webmineral - Levinsonite- (Y)
- Mindat - Levinsonite- (Y)
- American-Mineralogist-Crystal-Structure-Database - Levinsonite- (Y)
Individual evidence
- ↑ a b c d e f g h i j k l m n o p q r Roland C. Rouse, Donald R. Peacor, Eric J. Essene, T. Dennis Coskren, Robert J. Lauf: The new minerals levinsonite- ( Y) [(Y, Nd, Ce) Al (SO 4 ) 2 (C 2 O 4 ) .12H 2 O] and zugshunstite- (Ce) [(Ce, Nd, La) Al (SO 4 ) 2 (C 2 O 4 ) · 12H 2 O]: Coexisting oxalates with different structures and differentiation of LREE and HREE . In: Geochimica et Cosmochimica Acta . tape 65 , 2001, p. 1101–1115 , doi : 10.1016 / S0016-7037 (00) 00568-8 .
- ↑ a b c d e T. Dennis Coskren, Robert J. Lauf: The Minerals of Alum Cave Bluff, Great Smoky Mountains, Tennessee . In: The Mineralogical Record 2000 . tape 31 , 2000, pp. 163-175 .
- ↑ a b c Joseph A. Mandarino: New Minerals . In: The Canadian Mineralogist . tape 39 , 2001, p. 1485 , doi : 10.2113 / gscanmin.39.5.1473 ( rruff.info [PDF; 412 kB ]).
- ^ A b Donald R. Peacor, Roland C. Rous, Eric J. Essene: Coskrenite- (Ce), (Ce, Nd, La) 2 (SO 4 ) 2 (C 2 O 4 ) · 8H 2 O, a new rare-earth oxalate mineral from Alum Cave Bluff, Tennessee: Characterization and crystal structure . In: The Canadian Mineralogist . tape 37 , 1999, pp. 1453–1462 ( rruff.info [PDF; 1.1 MB ]).
- ^ Levinsonite- (Y). In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America. 2001 ( PDF, 68 kB )
- ↑ Catalog of Type Mineral Specimens - L. (PDF 70 kB) In: docs.wixstatic.com. Commission on Museums (IMA), December 12, 2018, accessed August 29, 2019 .
- ↑ Mindat - Number of localities for Levinsonite- (Y)
- ↑ Find location list for Levinsonite- (Y) at the Mineralienatlas and at Mindat
- ^ Robert J. Lauf: Secondary Sulfate Minerals From Alum Cave Bluff: Microscopy and Microanalysis . 1st edition. Oak Ridge National Laboratory, Oak Ridge, Tennessee 1997, p. 1–43 ( web.ornl.gov [PDF; 44.4 MB ]). web.ornl.gov ( Memento of the original from September 13, 2016 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
