Paceit
| Paceit | |
|---|---|
| General and classification | |
| other names |
IMA 2001-030 |
| chemical formula | CaCu (CH 3 COO) 4 • 6H 2 O |
|
Mineral class (and possibly department) |
organic compounds / acetates |
|
System no. to Strunz and to Dana |
10.AA.30 ( 8th edition : IX / A.02) 02.50.07.02 |
| Similar minerals | Hoganite |
| Crystallographic Data | |
| Crystal system | tetragonal |
| Crystal class ; symbol | tetragonal-dipyramidal; 4 / m |
| Space group | I 4 / m (No. 87) |
| Lattice parameters | a = 11.155 (4) Å ; c = 16.236 (17) Å |
| Formula units | Z = 4 |
| Physical Properties | |
| Mohs hardness | 1.5 |
| Density (g / cm 3 ) | calculated: 1.472 |
| Cleavage | completely according to {100} and {110} |
| Break ; Tenacity | uneven |
| colour | dark blue |
| Line color | Light Blue |
| transparency | translucent |
| shine | Glass gloss |
| Crystal optics | |
| Refractive indices |
n ω = 1.439 (2) n ε = 1.482 (3) |
| Birefringence | δ = 0.0430 |
| Optical character | uniaxial positive |
| Other properties | |
| Chemical behavior | soluble in water |
Paceite is an extremely rare, secondary mineral from the mineral class of " organic compounds ". It crystallizes in the tetragonal crystal system with the composition CaCu (CH 3 COO) 4 · 6H 2 O, so it is chemically a salt of acetic acid . Paceite is formed by the influence of rotting, vegetable material on copper ores. So far only one site has been found in Australia.
So far, paceite could only be discovered in the form of dark blue crusts. Naturally occurring single crystals are not yet known. The mineral is comparatively soft with a Mohs hardness of 1.5 and a light blue line color .
Etymology and history
Paceite was named after the Australian mineral collector Frank L. Pace (* 1948) who was the first to find it in the Perilya Potosi Mine ( Broken Hill , New South Wales, Australia ). It was analyzed and described by DE Hibbs, Uwe Kolitsch, P. Leverett, JL Sharpe, PA Williams in 2002. In the same year it was officially recognized as a mineral by the International Mineralogical Association (IMA).
Acetates as naturally occurring minerals are extremely rare, although acetic acid is widespread in nature. Until hoganite and pacecite were recognized as minerals, calclacite was the only known representative of this class of substances, although it is of anthropogenic origin. Up until then it was assumed that calclacite would remain the only representative of the acetates and a purely natural formation of other acetates was considered very unlikely. With the recognition of paceite as a mineral by the IMA, it is the second known acetate mineral that was formed without anthropogenic influence.
Type material of the mineral is stored in the Broken Hill Geocentre in Broken Hill, the Australian Museum in Sydney and the Museum of Victoria in Melbourne .
classification
Since paceite was only discovered in 2002 and recognized as an independent mineral type, it is not yet listed in the 8th edition of the Strunz mineral classification, which has been outdated since 1977 . Only in the "Lapis mineral directory", which was last updated in 2018, which, out of consideration for private collectors and institutional collections, is still based on this classic system of Karl Hugo Strunz , the mineral received the system and mineral number. IX / A.02-18 . In the "lapis Classification", this corresponds to the class "Organic Compounds", where the department "salts of organic acids", where Paceit together with abelsonite , Calclacit , Chanabayait , Dashkovait , Earlandit , Formicait , Hoganit , Joanneumit , Julienit , Kafehydrocyanit , mellite and Pigotit forms the group "Other organic salts, including mellates , citrates and acetates ".
The 9th edition of Strunz's mineral systematics, valid since 2001 and updated by the International Mineralogical Association (IMA) until 2009, also assigns Paceit to the class of "organic compounds" and there to the department of "salts of organic acids". This is further subdivided according to the substance groups that form the basis of the respective mineral, so that paceite can be found in the sub-section "Acetate" according to its composition, where it is the only member of the unnamed group 10.AA.30 .
The systematics of minerals according to Dana also assigns the hoganite to the class and department of the same name of "organic minerals". Here he is together with Hoganit in the " Hoganitgruppe " with the system no. 50.02.07 within the sub-section "Salts of organic acids (mellitates, citrates, cyanates and acetates)".
Crystal structure
Hoganite crystallizes tetragonally in the space group I 4 / m (space group no. 87) with the lattice parameters a = 11.155 (4) Å and c = 16.236 (17) Å , as well as 4 formula units per unit cell .
properties
Since paceite is an extremely rare mineral, many of its physical parameters have not yet been determined. In particular, it should be noted that many properties relate to synthetically produced crystals, which differ in their chemical composition (copper content and crystal water content) from natural mineral.
Like Hoganite , paceite gradually releases its crystal water when heated and decomposes at temperatures above 400 ° C. However, it must be taken into account that the data refer to synthetic crystals with a different chemical composition.
Education and Locations
For paceite only the type locality Perilya Potosi Mine (Potosi Mine) in Broken Hill, New South Wales, Australia has become known. Here, paceite was formed next to hoganite in the so-called iron hat of the deposit through the reaction of weathered ores with decomposing vegetable material, especially with rotting leaves. Furthermore, the formation of decaying wooden structures in the corresponding mining facilities is discussed. It is important to the first users that the plant decomposition products were not caused by humans. The mineral evidently formed at the place of discovery and not afterwards, as with calclacite; it is therefore not a museum artifact.
Paceite is associated with hoganite, linarite , malachite , azurite , copper-containing smithsonite , cerussite , goethite , hematite and quartz .
See also
literature
- Paceite . 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; 65 kB ; accessed on August 29, 2019]).
Web links
- Mineral Atlas: Paceite
- Paceite. In: mindat.org. Hudson Institute of Mineralogy, accessed August 29, 2019 .
Individual evidence
- ↑ a b c d e f g h i j k l DE Hibbs, Uwe Kolitsch, P. Leverett, JL Sharpe, PA Williams: Hoganite and paceite, two new acetate minerals from the Potosi mine, Broken Hill, Australia . In: Mineralogical Magazine . tape 66 , no. 3 , June 2002, p. 459–464 , doi : 10.1180 / 0026461026630042 ( rruff.geo.arizona.edu [PDF; 116 kB ; accessed on August 29, 2019]).
- ↑ David Barthelmy: Paceite Mineral Data. In: webmineral.com. Retrieved on August 29, 2019 .
- ↑ Catalog of Type Mineral Specimens - P. (PDF 113 kB) In: docs.wixstatic.com. Commission on Museums (IMA), December 12, 2018, accessed August 29, 2019 .
- ↑ Ernest H. Nickel, Monte C. Nichols: IMA / CNMNC List of Minerals 2009. (PDF 1703 kB) In: cnmnc.main.jp. IMA / CNMNC, January 2009, accessed April 25, 2019 .
- ^ A b Anthony W. Musumeci, Ray L. Frost, Eric R. Waclawik: A spectroscopic study of the mineral paceite (calcium acetate) . In: Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy . tape 67 , no. 3–4 , 2007, pp. 649–661 , doi : 10.1016 / j.saa.2006.07.045 ( eprints.qut.edu.au [PDF; 845 kB ; accessed on August 29, 2019]).