Formicaite
| Formicaite | |
|---|---|
| General and classification | |
| other names |
IMA 1998-030 |
| chemical formula | Ca (HCOO) 2 |
|
Mineral class (and possibly department) |
Organic compounds |
|
System no. to Strunz and to Dana |
10.AA.05 ( 8th edition : IX / A.02) 02.50.06.01 |
| Similar minerals | Dashkovaite , calclacite |
| Crystallographic Data | |
| Crystal system | tetragonal |
| Crystal class ; symbol | tetragonal-trapazohedral; 422 |
| Room group (no.) | P 4 1 2 1 2 (No. 92) |
| Lattice parameters | a = 6.770 Å ; c = 9.463 Å |
| Formula units | Z = 4 |
| Physical Properties | |
| Mohs hardness | 1 |
| Density (g / cm 3 ) | measured: 1.9 (1); calculated: 1.93 (2) |
| Cleavage | completely after {100} |
| colour | white with a bluish tinge |
| Line color | White |
| transparency | translucent |
| shine | Glass gloss |
| Crystal optics | |
| Refractive indices |
n ω = 1.553 n ε = 1.573 |
| Birefringence | δ = 0.020 |
| Optical character | uniaxial positive |
| Other properties | |
| Chemical behavior | easily soluble in water |
| Special features | light blue fluorescence in short-wave UV light |
Formicait is a very rarely occurring mineral from the mineral class of " organic compounds ". It crystallizes in the tetragonal crystal system with the composition Ca (HCOO) 2 , so it is chemically a calcium formate . The largest crystals found so far were around 30 µm in size.
Etymology and history
The name Formicait goes back to the Latin word formica for ant . The same root can also be found in its chemical name calcium formate , which identifies it as the salt of formic acid (Latin acidum formicum ).
Was first discovered Formicait in Bor - deposit "Solongo" on the Baikal Rift Zone belonging Witimplateau in the Russian Republic of Buryatia and described in 1999 by NV Chukanov, SV Malinko , AE Lisitsyn, Dubinchuk VT, OV Kuz'mina and AE Zadov.
classification
In the meanwhile outdated, but still in use 8th edition of the mineral classification according to Strunz , formicaite belonged to the mineral class of "organic compounds" and there to the department of "salts of organic acids", where together with abelsonite , calclacite , dashkovaite , earlandite , hoganite , Julienit , Kafehydrocyanit , Mellit and Paceit the "Mellit-Julienit-Gruppe" with the system no. IX / A.02 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 Formicait to the class of "organic compounds" and there to the department of "salts of organic acids". However, this division is further subdivided according to the salt-forming acid, so that the mineral can be found according to its composition in the sub-division of " Acetates ", where it is the only member of the unnamed group 10.AA.05 .
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns the Formicait to the class of "organic minerals" and the department of the same name. Here he is the namesake of the "Formicait series" with the system no. 50.02.06 and the other member Dashkovait within the subdivision of " Salts of organic acids (Mellitate, Citrate, Cyanate and Acetate) ".
Crystal structure
Formicait crystallizes tetragonally in the space group P 4 1 2 1 2 (space group no. 92) with the lattice parameters a = 6.770 Å and c = 9.463 Å and 4 formula units per unit cell . Well-defined, tabular crystals are rare. Most often it occurs as small spherical aggregates. All the samples found so far were microscopic.
properties
Formicait is easily soluble in water and therefore not permanent. The hygroscopic crystals in the air at high humidity to dissolve .
Formicait shows a blue-white fluorescence when irradiated with short-wave UV light.
From a chemical point of view, Formicait is the calcium salt of formic acid . Even if Formicait is the salt of an organic acid, its formation is not necessarily linked to biological organisms. Calcium formate can be formed by purely inorganic compounds (see → Presentation of calcium formate ).
Education and Locations
Formicaite has so far only been detected in boron-containing skarns in Siberia. Here it occurs mainly as thin, gray-white veins, where it was probably deposited hydrothermally. The accompanying minerals include calcite , lizardite , frolovite and the various hydroborites.
In addition to its type locality "Solongo" deposit on the Witim Plateau, the mineral was only able to be found in the "Titovskoe" deposit in the Tas-Khayakhtakh mountain range in the Republic of Sakha (Yakutia) and in the East Siberia (as of 2012) "Novofrolovskoye" Bor copper deposit can be found near Krasnoturyinsk in Sverdlovsk Oblast.
use
While there are many uses for calcium formate, these are only hypothetical due to the extreme rarity of formicaite for the mineral.
See also
literature
- NV Chukanov, SV Malinko, AE Lisitsyn, VT Dubinchuk, OV Kuz'mina and AE Zadov: Formicaite Ca (HCO 2 ) 2 , a new mineral (Russian: ФОРМИКАИТ Са (НС02) 2 - НОВЫЙ МИНЕРАЛ ), Zapiski Vserosheskogo 128 (1999) (2), pp. 43–47 ( PDF 328.7 kB ; English short description with original title in Russian)
- John L. Jambor, Nikolai N. Pertsev, Andrew C. Roberts: New Mineral Names , in: American Mineralogist , Volume 85 (2000), pp. 1321–1325 ( PDF 79.4 kB )
Web links
Individual evidence
- ↑ a b Stefan Weiß: The large Lapis mineral directory. All minerals from A - Z and their properties . 5th completely revised and supplemented edition. Weise, Munich 2008, ISBN 978-3-921656-70-9 .
- ↑ a b c Webmineral - Formicaite
- ↑ a b c John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols: Formicaite , in: Handbook of Mineralogy, Mineralogical Society of America , 2001 ( PDF 63.6 kB )
- ↑ a b Mindat - Formicaite