Pyromorphite
| Pyromorphite | |
|---|---|
 |
|
| General and classification | |
| other names |
|
| chemical formula | Pb 5 [Cl | (PO 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) 08.41.04.01 |
| Similar minerals | Apatite , vanadinite , mimetite |
| Crystallographic Data | |
| Crystal system | hexagonal |
| Crystal class ; symbol | hexagonal dipyramidal; 6 / m |
| Space group | P 6 3 / m (No. 176) |
| Lattice parameters | a = 9.98 Å ; c = 7.35 Å |
| Formula units | Z = 2 |
| Frequent crystal faces | mostly {10 1 0}, {0001}; next to it {10 1 1}, {20 2 1}, {11 2 1} |
| Physical Properties | |
| Mohs hardness | 3.5 to 4 |
| Density (g / cm 3 ) | 6.7 to 7.1; if Ca-rich, decreasing to 6 |
| Cleavage | is missing |
| Break ; Tenacity | shell-like to uneven |
| colour | green, brown, yellow, white, gray, orange to red |
| Line color | White |
| transparency | transparent to translucent |
| shine | Diamond luster, fat luster |
| Crystal optics | |
| Refractive indices |
n ω = 2.058 n ε = 2.048 |
| Birefringence | δ = 0.010 |
| Optical character | uniaxial negative |
| Other properties | |
| Chemical behavior | soluble in nitric acid and potassium hydroxide |
Pyromorphite (also Grünbleierz , Braunbleierz or polychrome ) is a common mineral from the mineral class of " phosphates , arsenates and vanadates ". It crystallizes in the hexagonal crystal system with the composition Pb 5 [Cl | (PO 4 ) 3 ], so it is chemically a lead phosphate with chlorine as an additional anion .
Pyromorphite is transparent to translucent and develops predominantly long, prismatic to tabular or pyramidal crystals , but also radial, grape, needle or earthy to massive aggregates . The mineral comes in different colors, however green, brown and yellow tones are predominant. His line color , however, is always white. A fat-like to diamond-like shine appears on the surfaces of the crystals .
Etymology and history
The mineral has only been verifiably known since around the end of the 17th century and was named, among others, by Johann Martin Michaelis in 1693 in the catalog of the mineral collection of Johann Jacob Spener, who died in 1692, as "Grün-Bley-Ertz von der Tschopa" ( green lead ore or Latin minera saturni viridis and minera plumbi viridis ). The “Holy Trinity” pit near Zschopau in the south of Saxony is therefore considered to be a type locality of the mineral.
This lead ore, called “Plumbum arsenico mineralisatum, minera solida & crystallisata viridi”, was first scientifically described by the Swedish chemist and mineralogist Johan Gottschalk Wallerius in his work Mineralogia, eller Mineralriket in 1747 , whereby the arsenic assumed but not contained in the pyromorphite was only a guess the color or an incorrect analysis of the related mimetite . In the revised edition of his mineral system from 1778, this assumption as well as that of the possible sulfur content was corrected.
A correct analysis of the material from the “Holy Trinity” mine near Zschopau finally succeeded in 1784/85 Martin Heinrich Klaproth , who determined that it was a lead salt of phosphoric acid. He was also able to prove that different color varieties such as the siskin green lead ore from the "Holy Trinity" mine (Zschopau), the grass-green lead ore from Hofsgrund ( Hoffsgrund , today Oberried near Freiburg), the brown lead ore from Huelgoet ( Huelgoat , Bretagne), the yellow Lead ore from Wanlockhead (Scotland) and a gray-white lead ore from an unknown location have almost the same composition, apart from small tolerances.
The mineral received its now valid name pyromorphite in 1809 from Friedrich Hausmann after the ancient Greek words πῦρ [pûr] " fire " and μορφή [morpʰē] "form" (the etymology of which is unclear). The name refers to the strange property of pyromorphite, which melts into small spheres in front of the soldering tube , which then crystallize into a crystalline polyhedron shape. However, this name only found recognition and dissemination from 1837 when it was used by James Dwight Dana in his systematics.
classification
In the meantime outdated, but still in use 8th edition of the mineral classification by Strunz of Pyromorphite belonged to the mineral class of "Phopsphate, arsenates and vanadates" and then to the Department of "water clear phosphates with foreign anions " where he along with the minerals of apatite group as It is named after the independent "apatite pyromorphite group" with the other members Belovit- (Ce) , Belovit- (La) , Fermorit , Fluorcaphit , Hedyphan , Johnbaumit , Klinomimetesit , Kuannersuit- (Ce) , Mimetesit , Morelandit , Svabit , Turneaureit and Vanadinite 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 pyromorphite to the class of "phosphates, arsenates and vanadates" and there to the department of "phosphates, etc. with additional anions ; without H 2 O “. However, this section is further subdivided according to the size of the cations involved and the molar ratio of the other anions to the phosphate (arsenate, vanadate) complex, so that the mineral is classified in the sub-section “With only large cations; (OH etc.): RO 4 = 0.33: 1 ”can be found, where the“ apatite-pyromorphite group ”with the system no. 8.BN.05 and the other members Alforsit , Belovit- (Ce) , Belovit- (La), Klinomimetesit , Deloneit- (Ce) , Fermorit, Fluorcaphit, Hedyphan, Hydroxyl-Pyromorphit , Johnbaumit, Kuannersuit- (Ce), Mimetesit , Morelandite, Phosphohedyphane , Svabit, Turneaureit and Vanadinite.
The systematics of minerals according to Dana also assigns pyromorphite to the class of "phosphates, arsenates and vanadates" and there in the category of "anhydrous phosphates etc., with hydroxyl or halogen". Here he is the only namesake of the " pyromorphite group " with the system no. 41.08.04 and the other members mimetite, vanadinite and hydroxylpyromorphite within the subdivision of "Anhydrous phosphates etc., with hydroxyl or halogen and the general composition (A) 5 (XO 4 ) 3 Z q ".
Chemism
According to its ideal composition Pb 5 [Cl | (PO 4 ) 3 ], pyromorphite consists of 76.38% lead (Pb 2+ ), 2.61% chlorine (Cl), 6.85% phosphorus (P) and 14.15% % Oxygen (O). In natural pyromorphites, however, the lead can partly be replaced ( substituted ) by calcium (Ca 2+ ) and the phosphorus (P 5+ ) partly by arsenic (As 5+ ) .
Crystal structure
Pyromorphite crystallizes isotypically with apatite in the hexagonal crystal system in the space group P 6 3 / m (space group no. 176) with the lattice parameters a = 9.98 Å and c = 7.35 Å and 2 formula units per unit cell .
Varieties
Blue bleeding ore is a special pseudomorphism from galena to pyromorphite.
Other varieties are collieite , which contains around 4.1% vanadium oxide , arsenate- containing nussièrit and calcium and germanate- containing pyromorphites.
Calcium-rich varieties are also known as Ca pyromorphite or polyspherite or polysphaerite .
Education and Locations
Pyromorphite generally occurs near the surface of lead deposits. Here it arises secondarily as a weathering product of lead-containing minerals in connection with aqueous solutions that contain the phosphate. It is often accompanied by galena , cerussite , mimetite , barite , limonite , vanadinite and descloicite .
As a frequent mineral formation, pyromorphite can be found in many places, with around 1400 sites worldwide (as of 2012) known to date. Important deposits in Germany were or are, among others, the Friedrichssegen mines near Lahnstein, Rosenberg and Pfingstwiese near Bad Ems in the Rhineland-Palatinate Lahntal, as well as Schauinsland and Silbergründle ( Seebach (Baden) ) in the Black Forest in Baden-Württemberg. The prismatic crystals with curved prismatic surfaces that were found near Bad Ems are also known as the Emser barrel because of their habitus . In addition, the mineral occurred in many other locations in Baden-Württemberg and Rhineland-Palatinate as well as in Bavaria, Hesse, Lower Saxony, North Rhine-Westphalia, Saarland, Saxony-Anhalt, Saxony and Thuringia.
In Austria, pyromorphite has so far been found primarily in Carinthia ( Friesach , Hüttenberg ) and Styria ( Fischbacher Alpen , Weiz ), but also at some sites in Lower Austria, Salzburg and Tyrol.
In Switzerland, the mineral has so far only been found in the lead mine at Chammegg in the Haslital in the canton of Bern and at the Torrent de St.-Barthélemy near Evionnaz and near Bagnes in the canton of Valais.
Other locations are in Afghanistan, Argentina, Australia, Belgium, Bolivia, Brazil, Bulgaria, Burundi, Chile, China, Ecuador, France, Greece, Iran, Ireland, Isle of Man, Italy, Japan, Canada, Kazakhstan, the Democratic Republic of the Congo and the Republic of the Congo (Brazzaville), North and South Korea, Madagascar, Malawi, Morocco, Mexico, Namibia, New Caledonia, New Zealand, Poland, Portugal, Romania, Russia, Zambia, Sweden, Senegal, Zimbabwe, Slovakia, Spain, South Africa, Thailand, the Czech Republic, Tunisia, Hungary, the United Kingdom (Great Britain) and several states in the USA.
use
When enriched locally, pyromorphite is used together with other lead minerals as a raw material for the extraction of lead .
See also
literature
- Friedrich Klockmann : Klockmann's textbook of mineralogy . Ed .: Paul Ramdohr , Hugo Strunz . 16th edition. Enke, Stuttgart 1978, ISBN 3-432-82986-8 , pp. 629 (first edition: 1891).
- Petr Korbel, Milan Novák: Mineral Encyclopedia (= Villager Nature ). Nebel Verlag, Eggolsheim 2002, ISBN 978-3-89555-076-8 , p. 172 .
- H. von Philippsborn: Tables for determining the minerals according to external characteristics . 2nd edition, E. Schweizerbartsche Verlagbuchhandlung
- Gregor Markl : Pyromorphite, Mimetesite & Vanadinite . In: Christian Weise (ed.): ExtraLapis . tape 46 . Christian Weise Verlag, 2014, ISSN 0945-8492 .
Web links
- Mineralienatlas: Pyromorphit , Mineralienatlas: Mineralienportrait / Pyromorphit (Wiki)
- RRUFF Database-of-Raman-spectroscopy - Pyromorphite (English)
- American-Mineralogist-Crystal-Structure-Database - Pyromorphite (English)
Individual evidence
- ↑ a b c d e Hugo Strunz , Ernest H. Nickel : Strunz Mineralogical Tables. Chemical-structural Mineral Classification System . 9th edition. E. Schweizerbart'sche Verlagbuchhandlung (Nägele and Obermiller), Stuttgart 2001, ISBN 3-510-65188-X , p. 467 .
- ↑ Webmineral - Pyromorphite (English)
- ↑ a b c Helmut Schrätze , Karl-Ludwig Weiner : Mineralogie. A textbook on a systematic basis . de Gruyter, Berlin; New York 1981, ISBN 3-11-006823-0 , pp. 629 .
- ↑ a b c Hans Jürgen Rösler : Textbook of Mineralogy . 4th revised and expanded edition. German publishing house for basic industry (VEB), Leipzig 1987, ISBN 3-342-00288-3 , p. 638 .
- ↑ a b Pyromorphites at mindat.org (English)
- ↑ a b c d Thomas Witzke : Discovery of pyromorphite
- ↑ Mineral portrait / Pyromorphite (Wiki)
- ↑ Collierite at mindat.org (English)
- ↑ Nussièrite at mindat.org (English)
- ↑ Ca-bearing pyromorphites at mindat.org (English)
- ↑ Germanate-pyromorphite at mindat.org (English)
- ↑ Mineralienatlas: Polysphaerit
- ↑ Find location list for pyromorphite in the Mineralienatlas and Mindat