Natrochalcite

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Natrochalcite
Natrochalcite-rh3-35a.jpg
Up to 7 mm large, emerald green natrochalcite crystals from the "Mina de Chuquicamata " near Calama , Province of El Loa, Región de Antofagasta , Chile (step size: 7.3 cm × 5.5 cm × 4.5 cm)
General and classification
chemical formula
  • NaCu 2 (SO 4 ) 2 (OH) • H 2 O
  • NaCu 2 (SO 4 ) 2 (OH) • 2H 2 O
  • NaCu 2 [OH | (SO 4 ) 2 ] • H 2 O
  • NaCu 2 (H 3 O 2 ) (SO 4 )
  • Na [Cu 2+ 2 (OH) (H 2 O) (SO 4 ) 2 ]
Mineral class
(and possibly department) 		Sulphates (selenates, tellurates, chromates, molybdates and tungstates)
System no. to Strunz
and to Dana 		7.DF.15 ( 8th edition : VI / D.18)
08/31/01/01
Similar minerals Kaliochalcite
Crystallographic Data
Crystal system monoclinic
Crystal class ; symbol monoclinic prismatic; 2 / m
Space group C 2 / m (No. 12)Template: room group / 12
Lattice parameters a  = 8.809  Å ; b  = 6.187 Å; c  = 7.509 Å
β  = 118.74 °
Formula units Z  = 2
Frequent crystal faces {111}, {110}, {221}, {001}
Physical Properties
Mohs hardness 4.5 (VHN = 280 kg / mm 2 )
Density (g / cm 3 ) 3.49 (measured), 3.54 (calculated)
Cleavage very perfect after {001}
Break ; Tenacity uneven; brittle
colour light emerald green; green in transmitted light
Line color pale greenish to greenish white
transparency translucent to translucent
shine Glass gloss
Crystal optics
Refractive indices n α  = 1.649
n β  = 1.655
n γ  = 1.714
Birefringence δ = 0.065
Optical character biaxial positive
Axis angle 2V = 36 ° 48 ′ (measured); 38 ° (calculated)
Other properties
Chemical behavior Easily soluble in acids, but only very slowly soluble in water

Natrochalcite is a very rare mineral from the mineral class of " sulfates (and relatives, see classification)". It crystallizes in the monoclinic crystal system with the chemical composition NACU 2 (SO 4 ) 2 (OH) · H 2 O and is therefore chemically seen a hydrous sodium - copper - sulfate with an additional hydroxide .

At its {111} type locality, natrochalcite develops steep pyramidal crystals up to 1 cm in size as well as crystalline crusts and fibrous aggregates . The type locality of the mineral is 15 km from Calama remote porphyry copper deposit of the "Mina de Chuquicamata ", El Loa Province, Antofagasta Region, Chile, one of the largest copper open pit mines in the world is.

Etymology and history

Chile Exploration Co. in Chuquicamata on April 12, 1925
Kröhnkit accompanied by natrochalcite from Chuquicamata, Chile (step size: 2.8 cm × 2.1 cm × 1.8 cm)

At the beginning of the last century the mineralogical laboratory of Harvard University received material for closer examination from the Foote Mineral Company in Philadelphia , which came from the area of Chuquicamata near Calama , Región de Antofagasta , Chile . Later, when the intensive investigation revealed that some of the minerals were probably new and the scientific interest in this material became apparent, the manager of Foote Mineral Co. generously left all of the material to Harvard University. The minerals examined included bright emerald green crystals of a mineral that was described as natrochalcite by Charles Palache and Charles H. Warren in 1908 in the American Journal of Science and in a German translation in the German journal Zeitschrift für Krystallographie und Mineralogie . It was named after the chemical composition of "sodium" and the ancient Greek word χαλκός [ chalkos ] for "copper". The material was, as Palache stated thirty years later, "poor" - but he was able to confirm the essential findings of the original description with new material. This new material came from findings by OW Jarrell and arrived at Harvard University in the mid-1930s.

Natrochalcite was also the first representative of the tsumcorite group , which is sometimes also described as the natrochalcite group. The eponymous mineral tsumcorite was not discovered until 1964 and was not described until 1971, but the structure of natrochalcite turned out to be identical to that of tsumcorite.

The type material for natrochalcite (two cotypes) is stored under catalog numbers 97537 and 97538 in the collection of the Mineralogical & Geological Museum of Harvard University in Cambridge , Massachusetts , USA.

Natrochalcite should not be confused with “natrocalcite”. These are the names Christian Samuel Weiss used to designate a variety of Gaylussit and Georg Uttinger, royal Bavarian mining authority administrator of Sonthofen , a variety of Datolith .

classification

The current classification of the International Mineralogical Association (IMA) counts natrochalcite to the tsumcorite group with the general formula Me (1) Me (2) 2 (XO 4 ) 2 (OH, H 2 O) 2 , in which Me (1), Me (2) and X different positions in the structure of the minerals of the tsumcorite group with Me (1) = Pb 2+ , Ca 2+ , Na + , K + and Bi 3+ ; Me (2) = Fe 3+ , Mn 3+ , Cu 2+ , Zn 2+ , Co 2+ , Ni 2+ , Mg 2+ and Al 3+ and X = As 5+ , P 5+ , V 5+ and represent S 6+ . To Tsumcoritgruppe include not only Natrochalcit still Cabalzarit , Cobaltlotharmeyerit , Cobalttsumcorit , Ferrilotharmeyerit , Gartrellit , Helmutwinklerit , Kaliochalcit , Krettnichit , Lotharmeyerit , Lukrahnit , Manganlotharmeyerit , Mawbyit , Mounanait , Nickellotharmeyerit , Nickelschneebergit , Nickeltsumcorit , Phosphogartrellit , Rappoldit , Schneebergit , Thometzekit , Tsumcorit , Yancowinnait and Zinc Gartrellite .

Already in the now outdated, but still in use 8th edition of the mineral classification according to Strunz , natrochalcite belonged to the mineral class of "sulfates (including selenates , tellurates , chromates , molybdates and tungstates )" and there to the department of "anhydrous sulfates, with foreign anions " , where together with Kainit , Uklonskovit and Vonbezingit he created the Kainit-Natrochalcit-Group with the system no. VI / D.18 .

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 classifies natrochalcite in 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 , so that the mineral can be found according to its composition in the sub-section “With large and medium-sized cations” , where it is the only member of the unnamed group with the system no. 7.DF.15 forms.

The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns natrochalcite to the class of "sulfates, chromates and molybdates" and there to the category of "water-containing sulfates with hydroxyl or halogen". Here he is the only member of the unnamed group 08/31/01 within the subdivision of " Water-containing sulfates with hydroxyl or halogen with (A + B 2+ ) (XO 4 ) Zq × x (H 2 O) ".

Chemism

Four microprobe analyzes on natrochalcite resulted in mean values ​​of 42.23% CuO; 40.88% SO 3 ; 9.19% Na 2 O; 0.09% MgO; 0.22% F; 0.13% SiO 2 ; 0.07% ZnO; 0.13% K 2 O; 0.02% Al 2 O 3 ; 0.02% MnO; 0.02% FeO; 0.04% P 2 O 5 and 0.03% CaO. From them the empirical formula Na calculated 1.00 Cu 2.02 (S 0.995 O 4 ) 2 (OH) • H 2 O, which to NACU 2 (SO 4 ) 2 (OH) · H 2 was idealized O. This ideal formula requires Na 2 O contents of 6.99% ; 42.74% CuO, 43.01% SO 3 and 7.26% H 2 O. Already in 1989 microprobe analyzes on natrochalcite crystals from the "Mina Santiagina", Sierra Gorda, Chile (Smithsonian Institution, R7941), a substitution of Sodium determined by potassium in the range of ≈ 2% up to 7%, however, it was not until 2014 that potassium chalcite , the potassium- dominant analogue of sodium-dominated natrochalcite, was described. Since the intermediate potassium-sodium-sulfate (K 0.5 Na 0.5 ) Cu 2 (SO 4 ) 2 [(OH) (H 2 O)] is known as a synthetic compound, there is at least the theoretical possibility of a complete mixed crystal row between natrochalcite and kaliochalcite.

There are also numerous synthetic equivalents such as Me + Cu 2 (OH) (zO 4 ) • H 2 O with Me +  = Na, K, Rb and z = S, Se as well as Ag + Cu 2 (OH) (SO 4 ) 2 · H 2 O and Me + Cu 2 (OH) (SeO 4 ) 2 · H 2 O with Me +  = Ag, Tl, NH 4 .

Crystal structure

Natrochalcite crystallizes in the monoclinic crystal system in the space group C 2 / m (space group no. 12) with the lattice parameters a  = 8.809  Å ; b  = 6.187 Å; c  = 7.509 Å and β = 118.74 ° as well as two formula units per unit cell . Template: room group / 12

The crystal structure of natrochalcite is formed from layers parallel (001), which consist of linarite -like chains, which are connected by common corners of (SO 4 ) tetrahedra of one chain with CuO 4 (OH) (H 2 O) octahedra of the adjacent chain are connected. These layers are carried NaO 8 - polyhedron and hydrogen bonds linked. According to Giester & Zemann (1987), the hydrogen-containing species in the spaces should be written as (H 3 O 2 - ). According to Anton Beran, Gerald Giester and Eugen Libowitzky or Eugen Libowitzky and Anton Beran, natrochalcite also contains an H 3 O 2 group (see also the adjacent drawing), which is connected to copper atoms via two oxygen atoms. While each oxygen atom of a sulfate tetrahedron acts as an external proton acceptor , the two oxygen atoms of the H 3 O 2 - group are both donors and acceptors for the very strong central (internal) peudosymmetric hydrogen bond. The results of FTIR spectroscopic investigations of the hydrogen bond system of the H 3 O 2 - group indicate a non-centrosymmetric structure of this H 3 O 2 - group and confirm the occurrence of a very strong hydrogen bond with a split position of the hydrogen atom.

  • Structure of natrochalcite projected onto (010)

  • Structure of the representatives of the tsumcorite group using the example of natrochalcite

  • Hydrogen bonds in natrochalcite

Natrochalcite is isotypic (isostructural) to the monoclinic representatives of the tsumcorite group such as tsumcorite and lotharmeyerite as well as to the synthetic equivalents mentioned above.

properties

Costume and habitus of natrochalcite crystals (same colors represent the same surface shapes)
Natrochalcite crystal drawing 1.png
natrochalcite crystal with little area
Natrochalcite crystal drawing 2.png
large natrochalcite crystal

morphology

At the type locality according to {111}, natrochalcite develops steep pyramidal crystals with a maximum size of 1 cm, on which the costume-determining prisms {111}, {110} and {221} as well as the basic pinacoid {001} have been identified (see the adjacent crystal drawings). The crystals are usually grown on the bedrock in such a way that parts of the prisms are formed and an oscillating striation occurs parallel to the edges between {111} and {221}. The crystals of the natrochalcite can be found either isolated - and then also as double ends - or in firmly adhering crusts on the white dike rock.

Other surface shapes observed are the pinacoid {010} and the prisms {112}, {331}, { 1 11} and { 2 11}. The pinacoid {100} and the prisms { 2 11} and { 7 12} were also detected on crystals found later . While the surface shapes {111} and {110} are usually well developed, the surfaces of the other shapes are usually only small and often not in their full number.

In addition to the crust-like aggregates mentioned, natrochalcite is also found in fibrous aggregates, which - similar to plaster of paris or fibrous celestine - are developed in ducts up to 2 cm thick, perpendicular to the ointment ligaments .

physical and chemical properties

The crystals of Natrochalchite are light emerald green, while their line color is pale green to greenish white. The surfaces of the translucent to transparent crystals have a glass-like sheen , which  agrees well with the values ​​for the refraction of light (n α = 1.649, n γ  = 1.714). Under the microscope , the mineral shows green hues without any pleochroism in the transmitted light .

Natrochalcite has a very perfect cleavage according to (001). Due to its brittleness , however , it breaks like amblygonite , with the fracture surfaces being uneven. With a Mohs hardness of 4.5, the mineral is one of the medium-hard minerals, so it stands between the reference minerals fluorite (hardness 4) and apatite (hardness 5) and, like these, can be easily scratched with a pocket knife more (fluorite) or less (apatite) . The measured density for natrochalchite is 3.49 g / cm³, the calculated density is 3.54 g / cm³.

The mineral crackles in front of the soldering tube and very easily melts into a black pearl. In a closed tube, natrochalcite releases acidic water and melts to a dark enamel . It is easily soluble in acids , but only very slowly soluble in H 2 O.

Education and Locations

Emerald green natrochalcite crystals up to 6 mm in size on a porphyry matrix
Natrochalcite on matrix (field of view 4 mm)

Natrochalcite is a typical secondary mineral that forms in arid climates in the oxidation zone of copper deposits . At the type locality Chuquicamata, the natrochalcite was first found in a dismantled and abandoned vein on a quartz-sericite matrix or completely embedded in chalcanthite. Later, when the huge open-cast mine of Chuquicamata was being built, the mineral was found in fibrous fillings of veins in addition to beautiful steps.

Paragenesis minerals from the original find in Chuquicamata are brochantite , atacamite and chalcanthite , but not a crowning kit. In the second described Natrochalcit Fund was fused with Antlerit, gypsum and Kröhnkit and bloedite . Leightonite , Paratacamite and solid copper are given as additional accompanying minerals .

As a very rare mineral formation, natrochalcite could only be described from seven sites so far (status 2018). As type locality classical applies Porphyry Copper Deposit ( English Porphyry Copper Deposit ) of the "Mina de Chuquicamata" in Calama, El Loa Province, Antofagasta Region , Chile . Other sites also located in Chile are the “Mina Fortuna” copper mine to the east of Baquedano and the “Mina Lomas Bayas” porphyry copper deposit, which has been in production since 1998 and is 93 km east-northeast of Antofagasta, both in the province of Antofagasta, Región de Antofagasta. With the "Mina Santiagina" in the Sierra Gorda there is another site in Chile, which is not mentioned in the relevant site compilations. It may be the "Mina Bella Santiaguina" - an old copper mine in the Sierra Gorda District and also in the province of Antofagasta.

Natrochalcit found himself also in various fumaroles on Second cinder cone on the north breakthrough of the Great fissure eruption (Great Fissure), volcano Tolbachik ( coordinates of the volcano Tolbachik ), Kamchatka , Far Eastern Federal District , Russia .

In the United States , the mineral was found in the Ag-Pb-Cu-Zn-Mo-Fluorite mine of the "Empire Mine" near Tombstone in the Tombstone District, Tombstone Hills , Cochise County in Arizona , and in the former U-Cu mine of the " Blue Lizard Mine ”, Red Canyon, White Canyon District, San Juan Co. , Utah .

The only European site for natrochalcite is the "Cantiere Vallone" of the "Miniera di Capo Calamita" near Capoliveri , Elba Island , Livorno Province , Tuscany region in Italy . Occurrences of natrochalcite in Germany , Austria or Switzerland are therefore not known.

use

Because of its rarity, natrochalcite is only of interest to the mineral collector. The anionic layer structure [Cu 2 (OH) (H 2 O) (SO 4 ) 2 ] - with charge compensation by Na + , which is a synthetic equivalent of natrochalcite, is used as an anode material for both lithium-ion batteries as well as sodium ion accumulators are discussed.

See also

literature

Web links

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

Individual evidence

  1. ↑ a b c d e f Gerald Giester: The crystal structures of Ag + Cu 2 (OH) (SO 4 ) 2 · H 2 O and Me + Cu 2 (OH) (SeO 4 ) 2 · H 2 O [Me +  = Ag, Tl, NH 4 ], four new representatives of the natrochalcite type, with a note on natural natrochalcite . In: Journal of Crystallography . tape 187 , no. 3-4 , 1989, pp. 239-247 , doi : 10.1524 / zkri.1989.187.3-4.239 .
  2. ↑ a b c d e f g h i j k l Natrochalcite . In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America . 2001 ( handbookofmineralogy.org [PDF; 67  kB ; accessed on January 24, 2018]).
  3. ↑ a b c d Mindat - Natrochalcite
  4. ^ 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.  407 .
  5. ↑ a b Eugen Libowitzky, Anton Beran: IR Spectroscopic characterization of hydrous species in minerals. In: Notes in Mineralogy Vol. 6 Spectroscopic Methods in Mineralogy (Anton Beran, Eugen Libowitzky, Ed.) . 1st edition. Eötvös University Press, Budapest 2004, ISBN 963-463-662-4 , p. 247-250 .
  6. ^ A b Frank C. Hawthorne , Sergey V. Krivovichev, Peter C. Burns: The Crystal Chemistry of Sulfate Minerals . In: Charles N. Alpers, John L. Jambor, D. Kirk Nordstrom (Eds.): Sulfate Minerals: Crystallography, Geochemistry, and Environmental Significance (=  Reviews in Mineralogy and Geochemistry . Volume  40 ). 2000, ISBN 978-0-939950-52-2 , pp. 1-112 , doi : 10.2138 / rmg.2000.40.1 ( minsocam.org ).
  7. ↑ a b c Igor V. Pekov, Oleg I. Siidra, Nikita V. Chukanov, Vasiliy O. Yapaskurt, Dmitriy I. Belakovskiy, Mikhail N. Murashko, Evgeny G. Sidorov: Kaliochalcite, KCu 2 (SO 4 ) 2 [( OH) (H 2 O)], a new tsumcorite-group mineral from the Tolbachik volcano, Kamchatka, Russia . In: European Journal of Mineralogy . tape 26 , no. 4 , 2014, p. 597-604 , doi : 10.1127 / 0935-1221 / 2014 / 0026-2394 ( researchgate.net [PDF; 406 kB ; accessed on January 24, 2018]).
  8. ↑ a b c d e f g h i j k l m n o p q r Charles Palache , Charles H. Warren: Kroehnkite, natrochalcite (a new mineral), and other sulphates from Chile . In: American Journal of Science . tape  26 , 1908, pp. 342-348 , doi : 10.2475 / ajs.s4-26.154.342 .
  9. ↑ a b Web mineral - natrochalcite
  10. ^ Charles Palache , Charles H. Warren: Kröhnkit, Natrochalcit (a new mineral) and other sulphates from Chile . In: Journal for Crystallography and Mineralogy . tape  45 , no. 6 , 1908, pp. 529-538 , doi : 10.1524 / zkri.1908.45.1.529 .
  11. ↑ a b c d e f Charles Palache : Kroehnkite and natrochalcite from Chile . In: American Journal of Science . tape  237 , 1939, pp. 447-455 , doi : 10.2475 / ajs.237.7.447 .
  12. ^ Robert Krickl, Manfred Wildner: Crystal chemistry of synthetic Co- and Ni-analogues of natrochalcite - the shortest known hydrogen bonds among mineral-type compounds Part I: Single-crystal X-ray structures . In: European Journal of Mineralogie . tape 19 , 2007, pp. 805-816 , doi : 10.1127 / 0935-1221 / 2007 / 0019-1770 .
  13. ^ Yongbo W. Yang, Stanley H. Evans, Robert T. Downs, Hexiong Yang: Lotharmeyerite, Ca (Zn, Mn) 2 (AsO 4 ) 2 (H 2 O, OH) 2 . In: Acta Crystallographica Section E Structure Reports . E68, 2012, p. i9-i10 , doi : 10.1107 / S1600536811054286 .
  14. ↑ Catalog of Type Mineral Specimens - N. (PDF 61 kB) In: docs.wixstatic.com. Commission on Museums (IMA), December 12, 2018, accessed August 29, 2019 .
  15. ^ Ernst Friedrich Glocker : Outline of mineralogy, including geognosy and petrefacts. For higher educational establishments and for private use . 1st edition. Johann Leonhard Schrag, Nuremberg 1839, p.  377–384 ( available online in Grundriß der Mineralogie, including Geognosie and Petrefactenkunde , p. 673 ff. In the Google book search).
  16. ^ Georg Uttinger: From a letter from Mr. Bergverwesers Uttinger in Sonthofen from September 15, 1809 . In: New year books of mining and metallurgy . tape II . Steinische Buchhandlung, Nuremberg 1812, p. 278–3290 ( available online in Neue Jahrbücher der Berg- und Hüttenkunde , pp. 289 ff. In the Google book search).
  17. ↑ Werner Krause, Klaus Belendorff, Heinz-Jürgen Bernhardt, Catherine McCammon, Herta Effenberger, Werner Mikenda: Crystal chemistry of the tsumcorite-group minerals. New data on ferrilotharmeyerite, tsumcorite, thometzekite, mounanaite, helmutwinklerite, and a redefinition of gartrellite . In: European Journal of Mineralogy . tape 10 , no. 2 , 1998, p. 179-206 , doi : 10.1127 / ejm / 10/2/0179 .
  18. ↑ RRUFF - Natrochalcit
  19. ^ A b Anton Beran, Gerald Giester, Eugen Libowitzky: The hydrogen bond system in natrochalcite-type compounds - an FTIR spectroscopic study of the H 3 O - unit . In: Mineralogy and Petrology . tape 61 , no. 1-4 , 1997, pp. 223-235 , doi : 10.1007 / BF01172486 .
  20. ↑ Gerald Giester, Josef Zemann : The crystal structure of the natrochalcite-type compounds Me + Cu 2 (OH) (zO 4 ) 2 · H 2 O [Me +  = Na, K, Rb; z = S, Se], with a special reference to the hydrogen bonds . In: Journal of Crystallography . tape 179 , no. 1-4 , 1989, pp. 431–442 , doi : 10.1524 / zkri.1987.179.14.431 ( rruff.info [PDF; 484 kB ; accessed on January 24, 2018]).
  21. ↑ Mindat - Number of sites for natrochalcite
  22. ↑ a b c d e list of locations for natrochalcite in the Mineralienatlas and Mindat
  23. ↑ Zhen Liu, Huajun Zhou, Simon S. Ang, Jian-Jun Zhang: Evaluation of Low-cost Natrochalcite Na [Cu 2 (OH) (H 2 O) (SO 4 ) 2 ] as an anode material for Li and Na -ion ​​batteries . In: Electrochimica Acta . tape 211 , 2016, p. 619–626 , doi : 10.1016 / j.electacta.2016.05.129 .