Pseudomalachite
| Pseudomalachite | |
|---|---|
 |
|
| General and classification | |
| other names |
|
| chemical formula | Cu 5 [(OH) 4 | (PO 4 ) 2 ] |
|
Mineral class (and possibly department) |
Phosphates, arsenates and vanadates |
|
System no. to Strunz and to Dana |
8.BD.05. ( 8th edition : VII / B.11) 41.4.3.1 |
| Similar minerals | Malachite (name!), Cornwallite, Libethenite |
| Crystallographic Data | |
| Crystal system | monoclinic |
| Crystal class ; symbol | monoclinic prismatic; 2 / m |
| Space group | P 2 1 / c (No. 14) |
| Lattice parameters |
a = 4.47 Å ; b = 5.75 Å; c = 17.03 Å β = 91.0 ° |
| Formula units | Z = 2 |
| Frequent crystal faces | {110}, {201}, {311}, {100}, {001} |
| Twinning | with the twin plane (100) |
| Physical Properties | |
| Mohs hardness | 4.5-5 |
| Density (g / cm 3 ) | 4.15-4.35 (measured); 4.34 (calculated) |
| Cleavage | little clear after (010) |
| Break ; Tenacity | splintery, mussel-like; brittle |
| colour | Chip to pistachio green with blackish green spots |
| Line color | chip green; lighter than the mineral color |
| transparency | translucent |
| shine | greasy to resinous glass gloss |
| Crystal optics | |
| Refractive indices |
n α = 1.789-1.80 n β = 1.835-1.86 n γ = 1.845-1.88 |
| Birefringence | δ = 0.056-0.08 |
| Optical character | biaxial negative, rarely biaxial positive |
| Axis angle | 2V = 46 ° –50 ° (measured) |
| Pleochroism | weak from X = bluish green to pale green; Y = yellowish green; Z = deep bluish green to bluish green |
| Other properties | |
| Chemical behavior | soluble in acids, water release in the flask, meltable in front of the soldering tube |
Pseudomalachite (also Lunnit, Ehlit, Prasin or Thrombolite and many other outdated names) is a rather seldom occurring mineral from the mineral class of " phosphates , arsenates and vanadates ". It crystallizes in the monoclinic crystal system with the composition Cu 5 [(OH) 4 | (PO 4 ) 2 ], so chemically speaking it is a copper phosphate with additional hydroxide ions .
The rarely occurring, up to 6 mm large, prismatic to tabular, often rounded crystals of pseudomalachite are translucent and show different shades of green. Much more common are radiating-fibrous aggregates in grape-like form and with a smooth surface.
Etymology and history
Pseudomalachite was discovered in the Westerwald , Rhineland-Palatinate , Germany , more precisely in the Virneberg mine not far from Rheinbreitbach near Linz am Rhein , and described in 1813 by Johann Friedrich Ludwig Hausmann . He named the mineral because of its appearance deceptively similar to malachite and after the Greek word ψενδής [pseudos] for "false" - put together, "false malachite".
classification
In the now outdated, but still in use 8th edition of the mineral classification according to Strunz , the pseudomalachite belonged to the division of "anhydrous phosphates, with foreign anions F, Cl, O, OH", where together with arsenoclasite , cornubite , gatehouseit , ludjibaite , cornwallite , Reichenbachit , Reppiait and Turanit form the unnamed group VII / B.11 .
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 pseudomalachite 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 additional anions to the phosphate, arsenate or vanadate complex (RO 4 ), so that the mineral is classified in the sub-section “With only medium-sized cations; (OH etc.): RO 4 = 2: 1 “can be found, where only together with Cornwallite and Reichenbachite the“ pseudomalachite group ”with the system no. 8.BD.05 forms.
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns pseudomalachite to the class of "phosphates, arsenates and vanadates" and there to the category of "anhydrous phosphates etc., with hydroxyl or halogen". Here it can be found together with Reichenbachite and Ludjibaite in the unnamed group 04/04/03 within the subsection “ Anhydrous phosphates etc., with hydroxyl or halogen with (AB) 5 (XO 4 ) 2 Z q ”.
Crystal structure
Pseudomalachite crystallizes isotypically with cornwallite in the monoclinic crystal system in the space group P 2 1 / c (space group no. 14) with the lattice parameters a = 4.47 Å ; b = 5.75 Å; c = 17.03 Å and β = 91.0 ° and two formula units per unit cell .
In the crystal structure of pseudomalachite, highly distorted [CuO 6 ] octahedra are linked by common edges in such a way that they form two distinct types of infinite chains parallel to b. These chains are alternately linked - again via common octahedron edges - so that they form layers to the bc-plane. Disturbed [PO 4 ] tetrahedra link these layers, although the exact position of the hydrogen ions in the structure has not been finally clarified.
properties
morphology
Pseudomalachite usually occurs in the form of grape-like crusts, hemispherical aggregates of microscopic crystals or sub-parallel aggregates with a glandular surface. Clear crystals are rare. They are tabular and often have uneven surfaces. In addition, pseudomalachite is found kidney, grape or massive with a radial fibrous structure and concentric banding, the fibers being stretched according to [010].
physical and chemical properties
The color of the pseudomalachite is chip to pistachio green with blackish green spots, its line color is chip green and significantly lighter than the mineral color. The gloss of the globular aggregates varies between greasy and resinous glass gloss, while the crystals have a pure glass gloss. With a Mohs hardness of 4 to 4.5, pseudomalachite is somewhat harder than fluorite. Pseudomalachite is soluble in acids such as HCl and HNO 3 as well as NH 4 (OH). When heated in a glass flask, it releases its water of hydration and shows a color change from green to black. Can be melted on carbon in front of the soldering tube, the melt bead that forms consists of metallic copper inside.
Modifications and varieties
The compound Cu 5 [(OH) 4 | (PO 4 ) 2 ] is trimorphic and occurs naturally in addition to the monoclinic crystallizing pseudomalachite as monoclinic crystallizing Reichenbachite as well as triclinic crystallizing Ludjibaite . Pseudomalachite is the natural phosphate analogue of Cornwallite.
Many of the mineral phases known today as pseudomalachite had different names in the past and were viewed as independent minerals, which is primarily due to the limited detection possibilities at the time. These include dihydrite (according to the wrongly assumed chemical composition with two moles of water), lunnite (according to the chemist Rev. F. Lunn), Ehlite (from Ehl am Rhein, according to the location), tagilite (from Nizhny Tagil , according to the location) , Prasin , phosphorochalcite (after the Greek word χαλκὁς [chalkos] for "copper") and thrombolite (from Rézbánya, after the Greek word θρόμβος [thrombos] for "coagulated body", because of the opal-like appearance). It was not until 1950 that detailed analyzes demonstrated that the dihydrite , lunnite , ehlite and prasin, which until then were considered to be independent minerals, were all pseudomalachite; the identity between tagilite and pseudomalachite was also established. The old names have been discredited by the IMA and are no longer considered valid mineral names.
Education and Locations
Pseudomalachite forms secondarily in the oxidation zone of hydrothermal sulphidic copper deposits . Other copper phosphates or arsenates such as chalcophyllite , cornetite , clinoclase , konichalcite , libethenite , olivite , strashimirite , tirolite , pyromorphite and apatite , but also sulfates such as brochantite and spangolite or carbonates such as azurite and malachite as well as chrysocolla , quartz , can be used as accompanying minerals . Chalcedony , tenorite , and iron oxyhydroxides occur.
As a rather rare mineral formation, pseudomalachite can sometimes be abundant at various sites, but overall it is not very common. So far (as of 2016) around 370 sites are known. In addition to its type locality , the Virneberg mine near Rheinbreitbach , the mineral occurred in Germany in several mines near Ehl not far from Linz on the Rhine , near Reichenbach in the Odenwald and on the “Silberbrünnle” mine in the Haigerach valley near Gengenbach and other deposits in the Black Forest . Pseudomalachite is mainly from Saxony from the “Altväter samt Eschig” mine near Sayda in Freiberg's deposit district and from the “Gottes Geschick Vereinigt Feld” mine at Graul near Schwarzenberg , from Thuringia from the “Arme Hilfe” mine near Ullersreuth in Vogtland and from Bavaria known from the copper mines of Lichtenberg near Bad Steben in Franconia . Particularly beautiful from the classic Mednorudjanskoe site near Nizhny Tagil in the Urals , Russia . From the oxidation zone of the deposit jezkazgan in central Kazakhstan Pseudomalachit in the form of 20 cm diameter reaching aggregates has become known. From “Podlipa” near Ľubietová (Libethen) and “Piesky” near Špania Dolina (Herrengrund) not far from Banská Bystrica , Slovakia . From Romania from Băița Bihor (formerly Rézbánya). In England from Caldbeck Fells, Cumbria , and a variety of pits in Cornwall including the Old Gunnislake Mine and East Gunnislake Mine (Calstock), Wheal Carpenter ( Gwinear ), the South Tolcarne Mine ( Camborne ), the Phoenix United Mine (Linkinghorne ), the Penberthy Croft Mine ( St Hilary ), Wheal Providence ( Gwinear ) and the Gunheath China Clay Pit near St Austell . From the "Miguel Vacas Mine" near Conceição, Vila Viçosa, Évora District, Portugal .
Important finds come from copper ore deposits in the Democratic Republic of the Congo such as "Kakanda-Est" and "M'sesa" near Likasi (Kambove District), "Kamoto East" and "Mutoshi" (Kolwezi District) and the "Kipushi Mine" near Kipushi, all in Katanga Province . Also from Mindouli, Department Pool , Republic of the Congo and from the deposits of “Bwana Mkubwa” near Ndola, “Nkana” near Kitwe and “Nchanga” near Chingola, Copperbelt Province , Zambia . In the United States from the "Perkiomen Mine" and the "Ecton Mine", Montgomery Co. , Pennsylvania ; the "Empire Nevada Mine", Lyon Co., Nevada and from the Lone Star Mine at Safford , Graham Co. , from Harquehala, La Paz Co. , and other locations in Arizona . From the huge open- cast copper mine in Chuquicamata , Antofagasta region and province , Chile . Particularly rich specimens come from Australia . Here are the "Mountain Glorious Mine" at Cloncurry in Queensland , the "West Bogan mine" at Tottenham and Broken Hill , both of New South Wales , as well as the "Burra Burra Mine" at Burra in the Mount Lofty Range, South Australia , to mention.
In Austria , pseudomalachite has so far been found at Gratlspitz near Brixlegg in Tyrol , Brandberg near Leoben and in the Tanzer quarry near Falkenstein in the Fischbacher Alps , both in Styria . Locations in Switzerland are not known.
Other important sites are in Argentina, Belgium, Brazil, Bulgaria, China, France, Ireland, Israel, Italy, Japan, Canada, Laos, Madagascar, Morocco, Mexico, Namibia, Norway, Peru, Poland, Portugal, Spain, South Africa and Uzbekistan.
use
As a pigment
Pseudomalachite has been used in the past as a green pigment in paintings and frescoes. It has been identified as a blue-green pigment in wall paintings from the Maya city of Calakmul , Mexico , dating from the period from 300 to 850 AD , and in burial accessories such as masks, miniatures, and vases found there. The mineral was also proven in Russian frescoes from the early 16th century in the Cathedral of the Birth of Mary in the fortified monastery of Ferapontow in the Russian Oblast of Vologda . Anhydrous copper (II) phosphate is still used today as a pigment (copper blue).
As a raw material
With a CuO content of 69.09%, pseudomalachite would be a rich and easily smeltable copper ore, but it is far too rare for that. Only in the past has the mineral been extracted as copper ore when it appeared in large quantities in the oxidation zones of copper ore deposits.
As a gem
In the past, pseudomalachite was also abraded as "Prasin". Today the mineral is in its natural form, cut as a cabochon and used as a decorative and decorative stone. In particular, the Eilat stone , a mixture of chrysocolla, malachite, azurite, turquoise and pseudomalachite from the "King Solomo Mine" in Israel , is sold as tumbled stone or cabochon.
See also
literature
- LG Berry (1950): On pseudomalachite and cornetite , In: American Mineralogist , Volume 35, pp. 365-385.
Web links
- Mineral Atlas: Pseudomalachite (Wiki)
- Web mineral - pseudomalachite
- Database-of-Raman-spectroscopy - Pseudomalachite
- American-Mineralogist-Crystal-Structure-Database - Pseudomalachite
- Russian Gemstones Encyclopedia: Malachite Group: Malachite, Azurite, Aurichalcite, Pseudomalachite
Individual evidence
- ↑ a b c d e f 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. 447 .
- ↑ a b c d e f g h Pseudomalachite , In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America , 2001 ( PDF 65 , 2 kB )
- ↑ a b c d Friedrich Klockmann : Klockmann's textbook of mineralogy . Ed .: Paul Ramdohr , Hugo Strunz . 16th edition. Enke, Stuttgart 1978, ISBN 3-432-82986-8 , pp. 630 (first edition: 1891).
- ^ Johann Friedrich Ludwig Hausmann : Handbook of Mineralogy . 1st edition. tape 3 . Vandenhoeck and Ruprecht, Göttingen 1813, p. 1035 . ( PDF, 490kB )
- ↑ GL Shoemaker, JB Anderson, E. Kostiner (1977): Refinement of the crystal structure of pseudomalachite , In: American Mineralogist , Volume 62, pp. 1042-1048 ( PDF, 605kB )
- ↑ http://www.mindat.org/min-3299.html Mindat - pseudomalachite
- ↑ Carl Hintze : Handbook of Mineralogy. First volume. Fourth section. Second half . 1st edition. Verlag Walter de Gruyter & Co., Berlin and Leipzig 1933, pp. 1097–1100.
- ^ LG Berry (1950): On pseudomalachite and cornetite , In: American Mineralogist , Volume 35, pp. 365-385.
- ↑ Mindat - Number of localities for pseudomalachite
- ↑ Find location list for pseudomalachite in the Mineralienatlas and Mindat
- ↑ RG Moreno, D. Strivay, B. Gilber (2008): Maya blue-green pigment found in Calakmul, Mexico: a study by Raman and UV-visible spectroscopy , In: Journal of Raman Spectroscopy , Volume 39 (8), S 1050-1056.
- ^ DA Scott: Copper and Bronze in Art. Corrosion, Colorants, Conservation . 1st edition. Getty Conservation Institute, Los Angeles 2002, ISBN 0-89236-638-9 , pp. 515 .
- ↑ a b August Breithaupt : Complete manual of mineralogy. Second volume. First Division of the Special Part . 1st edition. Arnoldische Buchhandlung Verlag, Dresden and Leipzig 1841, pp. 167–168.
- ↑ http://www.mindat.org/min-29162.html - Eilatstein