Nikischerit

Nikischerit
	Nikischerite from the Huanuni Mine, Huanuni , Dalence Province, Oruro, Bolivia (size: 4.4 × 4.1 × 1.1 cm)
General and classification
other names	IMA 2001-039
chemical formula	NaFe 2+ 6 Al 3 [(OH) 18 \| (SO 4 ) 2 ] • 12H 2 O
Mineral class; (and possibly department)	Sulfates (including selenates, tellurates, chromates, molybdates, and tungstates)
System no. to Strunz ; and to Dana	7.DD.35 ( 8th edition : VI / D.14) ; 01/31/02/02
Crystallographic Data
Crystal system	trigonal
Crystal class ; symbol	trigonal-rhombohedral; 3
Space group	R 3 (No. 148)
Lattice parameters	a = 9.347 Å ; c = 33,000 Å
Formula units	Z = 3
Twinning	not observed
Physical Properties
Mohs hardness	2
Density (g / cm 3 )	measured: 2.33; calculated: 2.34
Cleavage	completely after {001}
Break ; Tenacity	uneven; brittle
colour	dark green, brownish
Line color	light gray green
transparency	transparent to translucent
shine	Greasy gloss, matt
Crystal optics
Refractive indices	n ω = 1.560 (1) ; n ε = cannot be determined
Optical character	uniaxial negative

Nikischerite is a very rarely occurring mineral from the mineral class of "sulfates (including selenates, tellurates, chromates, molybdates and tungstates)" with the chemical composition NaFe ²⁺₆ Al ₃ [(OH) ₁₈ | (SO ₄ ) ₂ ] · 12H ₂ O and is therefore chemically seen a hydrous sodium - iron - aluminum - sulfate with additional hydroxide .

Nikischerite crystallizes in the trigonal crystal system and develops mica-like, leafy crystals , which are often connected to radial mineral aggregates of up to one centimeter in diameter. Fresh samples of the transparent to translucent mineral show a light to dark green color and a resin-like sheen on the crystal surfaces . Over time, however, it oxidizes, turns ocher brown and becomes matt.

Nikischerite is the Fe ²⁺ analog of Shigaite (Mn ²⁺₆ Al ₃ [(OH) ₁₈ | (SO ₄ ) ₂ ] · 12H ₂ O).

Etymology and history

Brownish, spherical nikischerite aggregate from the Huanuni mine (size: 0.6 cm × 0.6 cm × 0.5 cm)

Nikischerite was first discovered in the Huanuni Mine near Huanuni in the Bolivian Oruro Department and described in 2003 by Danielle Huminicki , Frank C. Hawthorne , Joel D. Grice, John Leslie Jambor , who named the mineral after its discoverer, the amateur mineralogist and mineral trader Anthony J. Nikischer (* 1949), named.

Type material of the mineral is kept in the Canadian Museum of Nature in Ottawa .

classification

In the outdated, but partly still in use 8th edition of the mineral classification according to Strunz , the nikischerite belonged to the mineral class of "sulfates, chromates, molybdates, wolframates" (including selenates and tellurates) and there to the department of "water-containing sulfates with foreign anions ", where he together with Lannonite , Metavoltin , Motukoreait , Natroglaukokerinit , Shigait , Slavíkit and Wermlandit the "Metavoltin group" with the system no. VI / D.14 .

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 nikischerite to the category of "sulfates (selenates, etc.) with additional anions, with H ₂ O". However, this is further subdivided according to the relative size of the cations involved and the crystal structure, so that the mineral can be classified according to its structure in the sub-section “with medium-sized cations; Layers of edge-sharing octahedra "can be found, where it together with Carrboydit , Glaukokerinit , Honessit , Hydrohonessit , Hydrowoodwardit , Motukoreait, Mountkeithit , Natroglaukokerinit, Shigait, wermlandite , Woodwardite , Zinkaluminit (Q), Zincowoodwardit the" Woodwarditgruppe " 7.DD.35 forms.

The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns nikischerite to the class of "sulfates, chromates and molybdates" and there to the category of "water-containing sulfates with hydroxyl or halogen". Here he is only together with Shigait in the unnamed group 01/31/02 within the subdivision “Hydrous sulfates with hydroxyl or halogen and (A ⁺ B ²⁺ ) _m (XO ₄ ) _p Z _q × x (H ₂ O), with m : p> 6: 1 “.

Crystal structure

Nikischerite crystallizes trigonally in the space group R 3 (space group no. 148) with the lattice parameters a = 9.347 Å and c = 33,000 Å as well as three formula units per unit cell . Template: room group / 148

Education and Locations

Nikischerite forms together with Vivianite through hydrothermal processes at relatively low temperatures and as a secondary mineral in the oxidation zone of sulphidic deposits . As a further accompanying minerals can pyrite , pyrrhotite , siderite and Cronstedtit occur.

The only known site to date is its type locality Huanuni Mine in Bolivia .

literature

Danielle Huminicki , Frank C. Hawthorne , Joel D. Grice, John Leslie Jambor : Nikischerite, a new mineral from the Huanuni tin mine, Dalence Province, Oruro Department, Bolivia. In: Mineralogical Record Volume 34 (2), March 2003, pp. 155-158
Danielle MC Huminicki, Frank C. Hawthorne: The crystal structure of nikischerite, NaFe2 + 6Al3 (SO4) 2 (OH) 18 (H2O) 12, a mineral of the shigaite group. In: The Canadian Mineralogist Volume 41, 2003, pp. 79–82 ( PDF 158.6 kB )
Peter Tarassoff: Who's who in mineral names: Anthony J. Nikischer (* 1949) In: Rocks and Minerals Volume 79 (3) (May / June 2004), pp. 190–191 ( limited preview available at search.proquest.com)

Web links

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

Individual evidence

↑ ^a ^b ^c Stefan Weiss: The large Lapis mineral directory. All minerals from A - Z and their properties . 6th completely revised and supplemented edition. Weise, Munich 2014, ISBN 978-3-921656-80-8 .
↑ ^a ^b Webmineral - Nikischerite
↑ ^a ^b ^c ^d Mineral data sheet on nikischerite at the Mineralogical Association of Canada ( Memento from October 23, 2016 in the Internet Archive ) (PDF 17.2 kB)
↑ ^a ^b Danielle MC Huminicki, Frank C. Hawthorne: The crystal structure of nikischerite, NaFe2 + 6Al3 (SO4) 2 (OH) 18 (H2O) 12, a mineral of the shigaite group. In: The Canadian Mineralogist Volume 41, 2003, pp. 79–82 ( PDF 158.6 kB )
^ ^A ^b ^c ^d John Leslie Jambor , Andrew C. Roberts: New Mineral Names. In: American Mineralogist Volume 88, 2003, pp. 1836–1840 ( PDF 74 kB ; Nikischerit p. 3)
↑ ^a ^b Mindat - Nikischerite
^ SJ Mills, AG Christy, J.-MR Génin, T. Kameda, F. Colombo: Nomenclature of the hydrotalcite supergroup: Natural layered double hydroxides In: Mineralogical Magazine Volume 76 (5), October 2012, pp. 1289-1336 ( PDF 5 MB ( memento of October 23, 2016 in the Internet Archive ); Nikischerit p. 20)
↑ Find location list for Nikischerite in the Mineralienatlas and in Mindat

[Lapis-1] Stefan Weiss: The large Lapis mineral directory. All minerals from A - Z and their properties . 6th completely revised and supplemented edition. Weise, Munich 2014, ISBN 978-3-921656-80-8 .

[Webmineral-2] Webmineral - Nikischerite

[DatenblattMAC-3] Mineral data sheet on nikischerite at the Mineralogical Association of Canada ( Memento from October 23, 2016 in the Internet Archive ) (PDF 17.2 kB)

[Huminicki-Hawthorne-4] Danielle MC Huminicki, Frank C. Hawthorne: The crystal structure of nikischerite, NaFe2 + 6Al3 (SO4) 2 (OH) 18 (H2O) 12, a mineral of the shigaite group. In: The Canadian Mineralogist Volume 41, 2003, pp. 79–82 ( PDF 158.6 kB )

[AM2003-88-5] A ^b ^c ^d John Leslie Jambor , Andrew C. Roberts: New Mineral Names. In: American Mineralogist Volume 88, 2003, pp. 1836–1840 ( PDF 74 kB ; Nikischerit p. 3)

[Mindat-6] Mindat - Nikischerite

[MM2012-76-7] SJ Mills, AG Christy, J.-MR Génin, T. Kameda, F. Colombo: Nomenclature of the hydrotalcite supergroup: Natural layered double hydroxides In: Mineralogical Magazine Volume 76 (5), October 2012, pp. 1289-1336 ( PDF 5 MB ( memento of October 23, 2016 in the Internet Archive ); Nikischerit p. 20)

[Fundorte-8] Find location list for Nikischerite in the Mineralienatlas and in Mindat