Earlshannonite

Earlshannonite
	Earlshannonite (red-brown, center) on mitridatite (brown) from the Foote Lithium County Mine, Kings Mountain (North Carolina) , USA (field of view 3 mm)
General and classification
other names	IMA 1983-010
chemical formula	MnFe 3+ 2 [OH \| PO 4 ] 2 • 4H 2 O
Mineral class; (and possibly department)	Phosphates, arsenates and vanadates
System no. to Strunz ; and to Dana	8.DC.15 ( 8th edition : VII / D.08) ; 11.42.18.04
Crystallographic Data
Crystal system	monoclinic
Crystal class ; symbol	monoclinic prismatic; 2 / m
Room group (no.)	P 2 1 / c (No. 14)
Lattice parameters	a = 9.91 Å ; b = 9.67 Å; c = 5.46 Å ; β = 93.9 °
Formula units	Z = 2
Frequent crystal faces	{110}, {100}, {011}
Twinning	after {100}
Physical Properties
Mohs hardness	3 to 4
Density (g / cm 3 )	measured: 2.90 (4); calculated: 2.92
Cleavage	indistinct
Break ; Tenacity	just
colour	dark reddish brown, yellowish brown, yellow orange to yellow
Line color	light brown
transparency	transparent
shine	Glass gloss
Crystal optics
Refractive indices	n α = 1.696 ; n β = 1.745 ; n γ = 1.765
Birefringence	δ = 0.069
Optical character	biaxial negative
Axis angle	2V = measured: 64 °; calculated: 62 °

Earlshannonite is a very rare mineral from the mineral class of "phosphates, arsenates and vanadates". It crystallizes in the monoclinic crystal system with the chemical composition MnFe ³⁺₂ [OH | PO ₄ ] ₂ · 4H ₂ O and is therefore chemically a water-containing manganese - iron - phosphate with additional hydroxide ions .

Earlshannonite is the manganese analogue of Whitmoreit (Fe ²⁺ Fe ³⁺₂ [OH | PO ₄ ] ₂ · 4H ₂ O) and forms a complete mixed crystal row with this . The mixed formula (Mn, Fe ²⁺ ) Fe ³⁺₂ [OH | PO ₄ ] ₂ · 4H ₂ O is therefore also given in various sources , with the elements Mn and Fe ²⁺ in the formula in each case can represent each other ( substitution , diadochie), but always stand in the same proportion to the other components of the mineral.

The mineral develops prismatic crystals up to about one millimeter in length, which are usually arranged in radial to spherical mineral aggregates . The surfaces of the transparent crystals have a glass-like sheen . Due to the formation of mixed crystals and foreign admixtures, the color can vary between dark reddish brown, light brown and yellow orange to yellow, but the line color is always light brown.

Etymology and history

Earlshannonite was first discovered in 1982 on the "Foote Lithium Co. Mine" (Foote Mine) landfill near Kings Mountain in the US state of North Carolina and in the "Cornelia Pit" near Hagendorf-Süd / Waidhaus in the Upper Palatinate Forest (Bavaria) in Germany .

The mineral was first described in 1984 by Donald R. Peacor , Pete J. Dunn and William B. Simmons , who named the mineral after the American mineralogist, chemist and curator of the US National Museum Earl Victor Shannon (1895-1981).

Type material of the mineral is kept in the National Museum of Natural History in Washington, DC, USA (Catalog No. 150168, R12832).

classification

Already in the outdated but still partially in use 8th edition of the mineral classification by Strunz of Earlshannonit belonged to the mineral class of "phosphates, arsenates and vanadates" and then to the Department of "water containing phosphates with foreign anions" where he along with Arthurit , Bendadait , Cobaltarthurit , Kleemanit , Mapimit , Ojuelait and Whitmoreit the "Arthurite group" with the system no. VII / D.08 .

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 earlshannonite to the category of “phosphates, etc. with additional anions; with H ₂ O “. However, this is further subdivided according to the relative size of the cations involved and the molar ratio of the additional anions to the phosphate, arsenate or vanadate complex (RO ₄ ), so that the mineral can be classified in the sub-section “With only medium-sized cations; (OH etc.): RO ₄ = 1: 1 and <2: 1 "can be found, where together with arthurite , bendadaite , cobalt arthurite , kunatite , ojuelaite and whitmoreit the" Whitmoreit group "with the system no. 8.DC.15 forms.

The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns earlshannonite to the class of "phosphates, arsenates and vanadates" and there to the category of "water-containing phosphates etc., with hydroxyl or halogen". Here he is also in the " Whitmoreit group " with the system no. 11/22/18 within the subsection “Water-containing phosphates etc., with hydroxyl or halogen with (AB) ₄ (XO ₄ ) ₃ Z _q × x (H ₂ O)”.

Education and Locations

Earlshannonite forms as a secondary mineral in lithium-rich granite - pegmatites . As accompanying minerals may include Frondelite , Jahnsit , Laueit various manganese oxides , Mitridatit , quartz and Rockbridgeite occur.

In addition to its type locality "Foote Lithium Co. Mine" near Kings Mountain, the mineral occurred in the United States in the LCA mine near Bessemer City in North Carolina and in the quarries "Emmons" near Greenwood , "Dunton Gem" near Newry and "Ryerson" Hill ”near Paris in Oxford County of Maine.

The Hagendorf south pegmatites and a nearby silver mine near Waidhaus in the Upper Palatinate Forest of Bavaria are so far (as of 2014) the only known sites in Germany.

Furthermore, Earlshannonite could only be discovered near Krásno nad Teplou (German Schönfeld ) and Bory in the Czech Republic and in the Owl Mountains (Polish Góry Sowie ) in Poland.

Crystal structure

Earlshannonite crystallizes monoclinically in the space group P 2 ₁ / c (space group no. 14) with the lattice parameters a = 9.91 Å ; b = 9.67 Å; c = 5.46 Å and β = 93.9 ° as well as two formula units per unit cell .

literature

Donald R. Peacor, Pete J. Dunn, William B. Simmons: Earlshannonite, the Mn analogue of whitmoreite, from North Carolina. In: The Canadian Mineralogist. Volume 22, 1984, pp. 471–474 ( PDF 421.3 kB )

Web links

Commons : Earlshannonite - collection of images, videos and audio files

Individual evidence

↑ ^a ^b ^c ^d ^e ^f Hugo Strunz , Ernest H. Nickel: Strunz Mineralogical Tables . 9th edition. E. Schweizerbart'sche Verlagbuchhandlung (Nägele and Obermiller), Stuttgart 2001, ISBN 3-510-65188-X , p. 498 .
↑ ^a ^b ^c ^d ^e ^f Earlshannonite , In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America . 2001 ( PDF 66.1 kB ).
↑ ^a ^b ^c Mindat - Earlshannonite
↑ Hans Jürgen Rösler : Textbook of Mineralogy . 4th revised and expanded edition. German publishing house for basic industry (VEB), Leipzig 1987, ISBN 3-342-00288-3 , p. 799 .
↑ Pete J. Dunn, James A. Ferraiolo: Memorial of Earl V. Shannon, 1895-1981. In: American Mineralogist. Volume 69, 1984, p. 993 ( PDF 220.5 kB ).
↑ Google author search: Earl Victor Shannon
↑ Find location list for Earlshannonite at the Mineralienatlas and at Mindat

[StrunzNickel-1] ↑ ^a ^b ^c ^d ^e ^f Hugo Strunz , Ernest H. Nickel: Strunz Mineralogical Tables . 9th edition. E. Schweizerbart'sche Verlagbuchhandlung (Nägele and Obermiller), Stuttgart 2001, ISBN 3-510-65188-X , p. 498 .

[Datenblatt-2] ↑ ^a ^b ^c ^d ^e ^f Earlshannonite , In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America . 2001 ( PDF 66.1 kB ).

[Mindat-3] Mindat - Earlshannonite

[Rösler-4] Hans Jürgen Rösler : Textbook of Mineralogy . 4th revised and expanded edition. German publishing house for basic industry (VEB), Leipzig 1987, ISBN 3-342-00288-3 , p. 799 .

[DunnFerraiolo-5] Pete J. Dunn, James A. Ferraiolo: Memorial of Earl V. Shannon, 1895-1981. In: American Mineralogist. Volume 69, 1984, p. 993 ( PDF 220.5 kB ).

[GoogleAutorShannon-6] Google author search: Earl Victor Shannon

[Fundorte-7] Find location list for Earlshannonite at the Mineralienatlas and at Mindat