Mimetite
| Mimetite | |
|---|---|
 |
|
| General and classification | |
| other names |
|
| chemical formula | Pb 5 [Cl | (AsO 4 ) 3 ] |
|
Mineral class (and possibly department) |
Phosphates, arsenates, vanadates |
|
System no. to Strunz and to Dana |
8.BN.05 ( 8th edition : VII / B.39) 08.41.04.02 |
| Crystallographic Data | |
| Crystal system | hexagonal |
| Crystal class ; symbol | hexagonal dipyramidal; 6 / m |
| Space group | P 6 3 / m (No. 176) |
| Lattice parameters | a = 10.211 Å ; c = 7.4185 Å |
| Formula units | Z = 2 |
| Frequent crystal faces | {10 1 0}, {0001} or {10 1 1}, rarely {11 2 1} or {21 3 1} |
| Twinning | very rarely after {11 2 2} |
| Physical Properties | |
| Mohs hardness | 3.5 to 4 |
| Density (g / cm 3 ) | measured: 7.24; calculated: 7.26 |
| Cleavage | indistinct after {10 1 1}; brittle |
| Break ; Tenacity | uneven to slightly scalloped |
| colour | colorless, white, gray, brown, honey yellow, orange yellow, greenish |
| Line color | White |
| transparency | transparent to translucent |
| shine | Diamond luster, fat luster, resin luster |
| Crystal optics | |
| Refractive indices |
n ω = 2.147 n ε = 2.128 |
| Birefringence | δ = 0.019 |
| Optical character | uniaxial negative |
| Other properties | |
| Chemical behavior | soluble in nitric acid and potassium hydroxide |
| Special features | piezoelectric; possible red fluorescence under UV light |
Mimetesite , also known under the outdated mining names arsenic lead pathway or green lead ore , is a rather rarely occurring mineral from the mineral class of phosphates , arsenates and vanadates . It crystallizes in the hexagonal crystal system with the chemical composition Pb 5 [Cl | (AsO 4 ) 3 ] and is therefore chemically a lead arsenate with additional chlorine ions .
Mimetesite develops prismatic or pyramidal crystals , but also grape-like, radial-rayed or earthy mineral aggregates , which can be either colorless or white, gray, brown, orange-yellow, greenish in color due to foreign admixtures or structural defects .
Etymology and history
The mineral was first described as an independent species in 1832 by the French mineralogist François Sulpice Beudant , who named it as mimetèse after the ancient Greek word μίμησις mímēsis for imitation or imitator due to its great similarity to pyromorphite .
In 1841 , August Breithaupt added the typical mineral ending -ite in his German mineral description, corresponding to mimetesite, and gave as synonyms pollachites arsenicus , arsenic lead spath (also arsenic lead spath ), green lead ore and arsenic lead spath . Wilhelm von Haidinger , on the other hand, chose the name Mimetite in his notes from 1845 , which is derived from the Greek word stem. However, this only prevailed in the English-speaking area.
The type of locality is the “Treuefreundschaft” mine near Johanngeorgenstadt in the Saxon Ore Mountains in Germany. In the meantime it has been established that the "Mimetesite" from Johanngeorgenstadt is monoclinic Mimetesite-M.
classification
Already in the outdated, but partly still in use 8th edition of the mineral classification according to Strunz , the mimetite belonged to the mineral class of "phosphates, arsenates and vanadates" and there to the department of "anhydrous phosphates, with foreign anions F, Cl, O, OH", where he together with Alforsit , Belovit- (Ce) , Belovit- (La) , carbonate fluorapatite , carbonate-hydroxyapatite , chlorine apatite , Fermorit , fluorapatite , Fluorcaphit , Hedyphan , hydroxyapatite , Hydroxylpyromorphit , Johnbaumit , Kuannersuit- (Ce) , Morelandit , Phosphohedyphane , Pyromorphit , strontium apatite , Svabit , Turneaureit and Vanadinit the "apatite group" with the system number. VII / B.39 .
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 the mimetite to the category of “phosphates etc. with additional anions; without H 2 O “. However, this is further subdivided according to the relative size of the cations involved and the molar ratio of the other anions to the phosphate, arsenate or vanadate complex (RO 4 ). According to its composition, the mineral is therefore in the subsection “With only large cations; (OH etc.): RO 4 = 0.33: 1 "to be found, where together with Alforsit, Belovit- (Ce), Belovit- (La), carbonate-fluorapatite, carbonate-hydroxylapatite, chlorapatite, fluorophosphohedyphane , fluorostrophite , Hydroxylapatite, Hydroxylapatit-M, Deloneit- (Ce), Fermorit, Fluorapatit, Fluorcaphit, Hedyphan, Hydroxylpyromorphit, Johnbaumit, Kuannersuit- (Ce), Morelandit, Phosphohedyphan, Pyromorphit, Svabit, Stronadelphit , Turneait-Gruppe, and Vanadite group the system no. 8.BN.05 forms.
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns the mimetite to the class of "phosphates, arsenates and vanadates" and there in the category of "anhydrous phosphates etc., with hydroxyl or halogen". Here it is together with hydroxylpyromorphite, pyromorphite and vanadinite in the " pyromorphite group " with the system no. 41.08.04 within the subsection "Anhydrous phosphates etc., with hydroxyl or halogen with (A) 5 (XO 4 ) 3 Z q ".
Crystal structure
Mimetesite crystallizes in the structure of apatite and occurs in several polytype varieties. Naturally occurring mimetite is usually hexagonal (mimetite-H, space group P 6 3 / m (space group no. 176) with the lattice parameters a = 10.211 Å and c = 7.4185 Å and two formula units per unit cell ).
Structural studies, e.g. B. on the mimetite from the type locality near Johanngeorgenstadt, showed that a monoclinic form still occurs, which is called clinomimetite or mimetite-M and crystallizes in the space group P 2 1 / b (no. 14, position 4) . Another polytype variety called Mimetite-2M ( P 2 1 (No. 4) ) could be detected on a Mimetite from China (Xianghualing, Linwu County, Hunan Province). Mimetesit-M and Mimetesit-2M were temporarily recognized as separate minerals, but were discredited in 2010.
properties
morphology
The mimetite often occurs in well-developed crystals, which can be either short to long prismatic elongated according to [0001], barrel or cylindrical shaped according to {10 1 0} or {1000} or pointed pyramidal shape. In addition, there are also earthy, granular, needle-like, grape-like or spherulitic, kidney-shaped and radial-ray mineral aggregates , often grown on its accompanying minerals.
Physical Properties
Mimetesite is piezoelectric , so, like quartz or tourmaline , it builds up an electrical voltage with periodically changing, elastic deformation.
Under UV light , some Mimetesite show a reddish fluorescence , similar to that of neon-colored highlighters .
Modifications and varieties
Well-known varieties are kampylite , a phosphorus-containing mimetesite with an orange-red color, which was found among other things as barrel-shaped crystals in Cumberland , and a fibrous or hairy aggregate called prixite .
Bellite , on the other hand, is a mixture of minerals made from quartz , mimetite and crocoite . By definition it is to be classified as rock .
Education and Locations
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It is a secondary mineral in oxidation zones in the Iron hat of lead - and zinc - deposits with arsenic-containing minerals and therefore often comes in paragenesis with various lead, arsenic and other minerals such as galena , Pyromorphite , Vanadinit , Wulfenit , Smithsonite and calcite ago .
In Germany, in addition to its type locality Johanngeorgenstadt in Saxony, the mineral was also found in Baden-Württemberg (Black Forest), Bavaria (Spessart), Hesse (Taunus), Lower Saxony (Harz), North Rhine-Westphalia (Bergisches Land, Eifel, Sauerland), Rhineland -Pfalz (Siegerland, Westerwald) and in Saxony-Anhalt (Harz).
Worldwide Mimetesite was already in Constantine in Algeria; Mendoza in Argentina; several regions of Australia ; Luxembourg Province in Belgium; La Paz in Bolivia; Smolyan Oblast and Vraza Oblast in Bulgaria; Chile ; People's Republic of China ; many regions in France ; Attica and Macedonia in Greece; Iran ; Ireland ; several regions in Italy ; Hokkaidō , Honshū and Kyūshū in Japan; Northwest Territory and Quebec in Canada; Kazakhstan ; Souss-Massa-Daraâ in Morocco; several regions in Mexico ; Namibia ; on the North Island of New Zealand; Akershus , Nordland and Telemark in Norway; Carinthia , Lower Austria , Salzburg , Styria and Tyrol in Austria; Poland ; several regions in Portugal ; Russia ; Dalarna and Värmland and Sweden; In the Swiss cantons of Glarus, Graubünden and Valais; South Africa ; several regions in Spain ; Songkhla in Thailand; Bohemia and Moravia in the Czech Republic; Hungary ; as well as found in many regions of Britain and the United States .
use
Mimetesite itself does not occur in mineable quantities, but is mined as a side-issue together with other lead ores for the extraction of lead .
See also
literature
- M. Pasero, AR Kampf, C. Ferraris, IV Pekov, JR Rakovan, TJ White: Nomenclature of the apatite supergroup minerals. In: European Journal of Mineralogy. Volume 22, 2010, pp. 163-179. ( PDF 722.5 kB )
- Martin Okrusch, Siegfried Matthes: Mineralogy: An introduction to special mineralogy, petrology and deposit science . 7th edition. Springer Verlag, Berlin / Heidelberg / New York 2005, ISBN 3-540-23812-3 , pp. 77 .
- Petr Korbel, Milan Novák: Encyclopedia of Minerals . Nebel Verlag, Eggolsheim 2002, ISBN 3-89555-076-0 , p. 173 .
- Friedrich Klockmann : Klockmann's textbook of mineralogy . Ed .: Paul Ramdohr , Hugo Strunz . 16th edition. Enke , Stuttgart 1978, ISBN 3-432-82986-8 , pp. 638 (first edition: 1891).
Web links
- Mineral Atlas: Mimetesite (Wiki)
Individual evidence
- ↑ a b c Hans Lüschen: The names of the stones. The mineral kingdom in the mirror of language . 2nd Edition. Ott Verlag, Thun 1979, ISBN 3-7225-6265-1 , p. 233, 275 .
- ↑ Webmineral - Mimetite (English)
- ↑ a b c American Mineralogist Crystal Structure Database (English)
- ↑ a b c d e f Mimetite. In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America. 2001. ( PDF 63.1 kB )
- ↑ a b c Mindat - Mimetite (English)
- ^ A b Paul Ramdohr , Hugo Strunz : Klockmanns textbook of mineralogy . 16th edition. Ferdinand Enke Verlag, 1978, ISBN 3-432-82986-8 , pp. 638 .
- ↑ Stefan Weiß: The large Lapis mineral directory . 5th edition. Christian Weise Verlag, Munich 2008, ISBN 978-3-921656-70-9 .
- ^ Johann Friedrich August Breithaupt: Complete manual of mineralogy. Arnoldische Buchhandlung, 1841, p. 289. ( limited preview in Google book search)
- ↑ a b Y. Dai, John M. Hughes, Paul B. Moore: THE CRYSTAL STRUCTURES OF MIMETITE AND CLINOMIMETITE, Pb 5 (AsO 4 ) 3 Cl. In: Canadian Mineralogist. Vol. 29, 1991, pp. 369-376. (PDF)
- ↑ Zhuming Yang, Kuishou Ding, Jeffrey de Fourestier, He Li: The crystal structure of mimetite-2M, a new polymorph of mimetite from Xianghualing tin-polymetallic orefield, Hunan Province, PR China. In: N. Jb. Miner. Dep. (J. Min. Geochem.). 190/2, 2013, pp. 229–235 (PDF)
- ↑ Mindat - Mimetite-M and Mimetite-2M
- ↑ Mineral Atlas: Prixit (Wiki)
- ↑ Mineral Atlas: Bellit (Wiki)
- ↑ Find location list for mimetesite in the Mineralienatlas and in Mindat