Sanromanite
| Sanromanite | |
|---|---|
 |
|
| General and classification | |
| other names |
IMA 2006-009 |
| chemical formula | Na 2 CaPb 3 [CO 3 ] 5 |
|
Mineral class (and possibly department) |
Carbonates and nitrates (formerly carbonates, nitrates and borates) |
|
System no. to Strunz and to Dana |
5.AC.30 ( 8th edition : V / B.07) 04/14/04/04 |
| Crystallographic Data | |
| Crystal system | hexagonal |
| Crystal class ; symbol | dihexagonal-pyramidal; 6 mm |
| Room group (no.) | P 6 3 mc (No. 186) |
| Lattice parameters | a = 10.570 (1) Å ; c = 6.651 (1) Å |
| Formula units | Z = 2 |
| Frequent crystal faces | {10 1 0} and {11 2 1} |
| Twinning | after (11 2 0) |
| Physical Properties | |
| Mohs hardness | 4th |
| Density (g / cm 3 ) | calculated: 5.20 |
| Cleavage | not observed |
| Break ; Tenacity | brittle |
| colour | colorless, greenish yellow |
| Line color | White |
| transparency | transparent |
| shine | Glass gloss |
| Crystal optics | |
| Refractive indices |
n ω = 1.80 n ε = 1.80 |
| Birefringence | δ = 0.018 |
| Optical character | uniaxial negative |
| Other properties | |
| Chemical behavior | Easily soluble in concentrated hydrochloric acid |
Sanrománit is a very rare mineral from the mineral class of "carbonates and nitrates" (formerly carbonates, nitrates and borates). It crystallizes in the hexagonal crystal system with the chemical composition Na 2 CaPb 3 [CO 3 ] 5 and is therefore chemically a sodium - calcium - lead - carbonate .
Sanrománit is transparent and develops needle-like crystals with a glass-like sheen on the surfaces, which are usually arranged in radial, artichoke-like aggregates . The fine crystal needles themselves are colorless, but aggregate forms appear in a greenish-yellow color.
Special properties
The mineral is easily soluble in concentrated hydrochloric acid . In concentrated nitric acid and sulfuric acid , it slowly decomposes.
Etymology and history
Sanrománite was first discovered in May 2003 by Arturo Molina in the Mina Santa Rosa, which is located about 15 kilometers southeast of Iquique in the Santa Rosa Huantajaya mining district in the Chilean region of Tarapacá . The mineral was scientifically described in 2007 by Jochen Schlüter, Thomas Malcherek and Dieter Pohl, who named it after the Chilean naturalist Francisco J. San Román (1834–1902).
The type material of the mineral is kept in the collection of the Mineralogical Museum Hamburg in Germany.
classification
In the outdated, but partly still in use 8th edition of the mineral classification according to Strunz , the sanrománite belonged to the common mineral class of "carbonates, nitrates and borates" and there to the department of "anhydrous carbonates [CO 3 ] 2− without foreign anions ", where he together with Burbankit , Calcioburbankit , Carbocernait , Khanneshit , Petersenit- (Ce) , Rémondit- (Ce) and Rémondit- (La) the "Burbankit series" with the system no. V / B.07 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), assigns the sanrománite to the reduced class of "carbonates and nitrates" (the borates form a separate class here), but also to the Department of “Carbonates without additional anions; without H 2 O “. However, this is further subdivided according to the predominant element group in the compound (alkali and / or alkaline earth metals), so that the mineral can be found in the sub-section “ Alkali and alkaline earth carbonates”, where it is only found together with burbankite, depending on its composition , Calcioburbankit and Khanneshit the "Burbankit group" with the system no. 5.AC.30 forms.
Also the systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns the Sanrománite to the common class of "carbonates, nitrates and borates" and there in the department of "anhydrous carbonates", like the outdated Strunz system. Here, however, it is also in the " Burbankit group (hexagonal) " with the system no. 04/14/04 within the sub-section "Anhydrous carbonates with a compound formula A 2+ B 2+ 2 (CO 3 ) 4 ".
Education and Locations
Sanrománit has so far only at its type locality discovered Mina Santa Rosa in Chile are where it is in the oxidation zone of polymetallic transition - deposit formed and there in paragenesis with anhydrite , calcite , Chalkonatronit , Juangodoyit , malachite and various sodium bicarbonates, such as, among others, Trona and nahcolite was found.
Crystal structure
Sanrománite crystallizes hexagonally in the space group P 6 3 mc (space group no.186 ) with the lattice parameters a = 10.570 (1) Å and c = 6.651 (1) Å as well as two formula units per unit cell .
See also
literature
- Jochen Schlüter, Thomas Malcherek, Dieter Pohl: Sanromanite, Na 2 CaPb 3 (CO 3 ) 5 , from the Santa Rosa mine, Atacama desert, Chile, a new mineral of the burbankite group. In: New Yearbook for Mineralogy - Treatises. Volume 183 Issue 2 (2007), pp. 117-121 doi : 10.1127 / 0077-7757 / 2007/0068
Web links
- Mineral Atlas: Sanrománit (Wiki)
- Mindat - Sanrománite
- Web mineral - Sanrománite
- American-Mineralogist-Crystal-Structure-Database - Sanrománite
Individual evidence
- ↑ a b c d e f g h Jochen Schlüter, Thomas Malcherek, Dieter Pohl: Sanromanite, Na 2 CaPb 3 (CO 3 ) 5 , from the Santa Rosa mine, Atacama desert, Chile, a new mineral of the burbankite group. In: New Yearbook for Mineralogy - Treatises. Volume 183 Issue 2 (2007), pp. 117-121 doi : 10.1127 / 0077-7757 / 2007/0068
- ↑ 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 .