Natroxalate

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Natroxalate
General and classification
other names

IMA 1994-053

chemical formula Na 2 (C 2 O 4 )
Mineral class
(and possibly department) 		Organic compounds / oxalates
System no. to Strunz
and to Dana 		10.AB.60 ( 8th edition : IX / A.01-05)
01.50.11.01
Crystallographic Data
Crystal system monoclinic
Crystal class ; symbol monoclinic prismatic; 2 / m
Room group (no.) P 2 / c (No. 13)
Lattice parameters a  = 10.426  Å ; b  = 5.255 Å; c  = 3.479 Å
β  = 93.14 °
Formula units Z  = 2
Physical Properties
Mohs hardness 3
Density (g / cm 3 ) 2.32
Cleavage completely after {100}
colour colorless, white, light yellow
Line color White
transparency transparent
shine Glass gloss
Other properties
Special features water soluble

Natroxalate is a very rare mineral from the mineral class of " organic compounds ". It crystallizes in the monoclinic crystal system with the chemical composition Na 2 (C 2 O 4 ), so from a chemical point of view it is a sodium oxalate or the sodium salt of oxalic acid .

Natroxalat usually develops colorless and transparent, tabular crystals up to about one centimeter in length. The streak color of the mineral is white and with a Mohs hardness of 3 it is one of the rather soft minerals.

Special properties

Natroxalate is readily soluble in water. Like all oxalates, it is not thermally stable . Above about 250 ° C it breaks down into sodium carbonate and carbon monoxide .

Etymology and history

The name is derived from the chemical composition ( sodium oxalate ). The etymological origin of oxalic acid goes back to the scientific name of wood sorrel (Oxalis acetosella) . This contains larger amounts of oxalic acid and the corresponding potassium salt.

The mineral was first described in 1994 by the Russian mineralogist AP Khomyakov.

In the same year it was recognized as a mineral by the IMA under the number IMA 1994-053. Type material is kept in the Saint Petersburg Mining Institute under number 2080/1 and in the Russian Academy of Sciences under number 1522.

classification

In the now outdated, but still in use 8th edition of the mineral classification according to Strunz , the natroxalate belonged to the mineral class of "organic compounds" and there to the department of "salts of organic acids", where together with Coskrenit- (Ce) , Glushinskit , Humboldtin , Levinsonite (Y) , lindbergite , minguzzite , moolooite , caoxite , novgorodovaite , oxammite , stepanovite , Weddellite , wheatleyite , whewellite , zhemchuzhnikovite 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 natroxalate to the class of "organic compounds" and there to the department of "salts of organic acids". However, this section is further subdivided according to the type of salt-forming acid , so that the mineral can be found in the sub-section "Oxalates" according to its composition, where it is the only member of the unnamed group 10.AB.60 .

The systematics of minerals according to Dana also assigns natroxalate to the class of "organic minerals" and there in the department of the same name. Here it is the only mineral to be found in the unnamed group 50.01.11 within the sub-section " Salts of organic acids (oxalates) ".

Education and Locations

So far, natroxalate has only been known from two sites (as of January 2013) in the Chibinen on the Kola Peninsula . Here it was found in mines near the Alluaiw and Kukiswumtschorr mountains .

Natroxalate occurs there in pegmatites . The pegmatites found there were hydrothermally converted. Therefore, they are rich in sodium and carbonates, from which natroxalate was formed. Even if Natroxalat is the salt of an organic acid, no biological processes were involved in its formation.

Crystal structure

Natroxalate crystallizes monoclinically in the space group P 2 / c (space group no. 13) with the lattice parameters a  = 10.426  Å ; b  = 5.255 Å; c  = 3,479 Å and β = 93.14 °, as well as two formula units per unit cell .

use

Due to the rarity of Natroxalate, there are no practical uses for this mineral. The sodium oxalate used in the chemical industry is produced exclusively synthetically.

See also

literature

  • AP Khomyakov (1996): Natroxalate, Na2C2O4, a new mineral , in: Zapiski Vserossiskogo Mineralogicheskogo Obshchetstva , Volume 125 (1) (1996), 126-132 (in Russian), brief description in English available online at minsocam.org (Mineralogical Society of America; PDF; 90 kB)
  • Natroxalate , in: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America , 2001 ( PDF 64.5 kB )

Web links

Individual evidence

  1. ^ A b D.A. Reed, MM Olmstead, Sodium oxalate structure refinement. Acta Cryst., (1981) 37, pp. 938-939
  2. ↑ AP Khomyakov, Zapiski Vserossiskogo Mineralogicheskogo Obshchetstva 125 (1996) (1), 126-132.
  3. ↑ Pekov, I. (1998) Minerals First discovered on the territory of the former Soviet Union p. 369 ff. Ocean Pictures, Moscow.
  4. ↑ GV Plekhanov St. Petersburg Mining Institute .
  5. ^ DA Reed, MM Olmstead, Sodium oxalate structure refinement. Acta Cryst., (1981) 37, pp. 938-939