Azurite
| Azurite | |
|---|---|
 |
|
| General and classification | |
| other names |
|
| chemical formula | Cu 3 (CO 3 ) 2 (OH) 2 |
|
Mineral class (and possibly department) |
Carbonates and nitrates |
|
System no. to Strunz and to Dana |
5.BA.05 ( 8th edition : V / C.01) 16a.02.01.01 |
| Similar minerals | Dumortierite , malachite , lapis lazuli |
| Crystallographic Data | |
| Crystal system | monoclinic |
| Crystal class ; symbol | monoclinic prismatic; 2 / m |
| Space group | P 2 1 / c (No. 14) |
| Lattice parameters |
a = 5.00 Å ; b = 5.85 Å; c = 10.35 Å β = 92.3 ° |
| Formula units | Z = 2 |
| Physical Properties | |
| Mohs hardness | 3.5 to 4 |
| Density (g / cm 3 ) | measured: 3.773 (3); calculated: 3.78 |
| Cleavage | complete, but interrupted after {011}; clearly after {100}; indistinct after {110} |
| Break ; Tenacity | shell-like |
| colour | deep blue ( azure ) |
| Line color | blue to light blue |
| transparency | transparent to opaque |
| shine | Glass to greasy gloss |
| Crystal optics | |
| Refractive indices |
n α = 1.730 n β = 1.758 n γ = 1.838 |
| Birefringence | δ = 0.108 |
| Optical character | biaxial positive |
| Axis angle | 2V = measured: 68 °; calculated: 64 ° |
| Pleochroism | distinctly light blue-dark blue |
| Other properties | |
| Chemical behavior | Easily soluble in dilute hydrochloric acid with release of CO 2 |
Azurite , also known under its mining name Bergblau , Kupferblau or Kupferlasur , is a frequently occurring mineral from the mineral class of "carbonates and nitrates". It crystallizes in the monoclinic crystal system with the chemical composition Cu 3 (CO 3 ) 2 (OH) 2 and is therefore chemically a basic copper carbonate .
Azurite is mostly found in the form of small crystals embedded in the rock with a prismatic, short columnar or tabular habit , but also occurs in the form of spherical, kidney or powdery mineral aggregates as well as fused with malachite . The mineral has a characteristic, deep blue color and its crystal surfaces have a glass- to fat-like sheen . Azurite leaves a blue to light blue line on the marking board .
With a Mohs hardness of 3.5 to 4, azurite is one of the medium-hard minerals. It is a little easier to scratch with a pocket knife than the reference mineral fluorite (4) .
Etymology and history
For the etymology of the mineral name (derived from azur ) see main article Azure blue .
Azurite has been known for more than 4,500 years. Already the Egyptians of the Old Kingdom around 2500 BC. BC used the powdered mineral as eye make-up ( khol or eye shadow ) and for wall paintings . Azurite was also found in the Maya wall paintings of Bonampak . With the Greeks the mineral was known as ὰρμένιον and with the Romans Latinized as Armenium or Armenian stone .
Azurit received its mineral name, which is still valid today, in 1824 from the French mineralogist François Beudant based on its color.
The synonym Chessylite was created due to the historical delivery location Chessy in the French department of Rhône .
classification
In the now outdated, but still in use 8th edition of the mineral classification according to Strunz , the azurite still belonged to the common mineral class of "carbonates, nitrates and borates" and there to the department of "anhydrous carbonates with foreign anions ", where together with rosasite it was the " Azurit-Rosasit-range “with the system no. V / C.01 and the other members aurichalcite , brianyoungite , chukanovite , georgeit , glaucosphere , hydrozincite , kolwezite , losyite , malachite , mcguinnessite , nullaginite , pokrovskite , sclarite and zinc rosasite .
The 9th edition of Strunz's mineral systematics , which has been in force since 2001 and is used by the International Mineralogical Association (IMA), classifies azurite in the reduced mineral class of "carbonates and nitrates" (the borates form a separate class here), but also in the department of “carbonates with additional anions; without H 2 O “. However, this is further subdivided according to the predominant metals in the compound, so that the mineral can be found according to its composition in the sub-section "With Cu , Co , Ni , Zn , Mg , Mn ", where it is the only member of the unnamed group 5 .BA.05 forms.
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns the azurite, like the outdated Strunz system, to the common class of “carbonates, nitrates and borates” and there to the category of “carbonates - hydroxyl or halogen”. Here he is the only member of the unnamed group 16a.02.01 within the subdivision “ 16a.02 Carbonates - hydroxyl or halogen with (AB) 3+ (XO 3 ) 2 Z q ”.
Crystal structure
Azurite crystallizes monoclinically in the space group P 2 1 / c (space group no. 14) with the lattice parameters a = 5.00 Å ; b = 5.85 Å; c = 10.35 Å and β = 92.3 ° and 2 formula units per unit cell .
Education and Locations
Exhibited in the Melbourne Museum
Azurite is a secondary mineral that is formed in the oxidation zone of sulphidic copper deposits through chemical weathering from chalcopyrite and other copper sulphides or copper ores in general . When it absorbs water, it also turns into green malachite and is therefore often found fused with it. Are also known pseudomorphs of malachite and azurite to copper as azurite. Azurite is also often a component of copper pechers . Depending on the location, azurite can occur in paragenesis with various minerals such as angelsite , antlerite , brochantite , calcite , chrysocolla , cerussite , cuprite ( red copper ore ), dolomite and smithsonite ( calamine ).
As a frequent mineral formation, azurite can be found at many sites, with around 5000 sites being known to date (as of 2014). In ancient times, Armenia , Cyprus and Andalusia in Spain were the main suppliers of azurite. Until the middle of the 17th century, Hungary was the most important azurite source in Europe. Later sources of supply, up to around the end of the 19th century, were Chessy near Lyon in France, Mechernich in the German Vulkaneifel and the mines near Alghero on the Italian island of Sardinia.
In Germany, azurite was found in Mechernich, where it was precipitated through sedimentation in the red sandstones there, in many places in the Black Forest (Baden-Württemberg), in the Thuringian-Franconian low mountain range , in the Odenwald and Spessart (Hesse), in the Harz Mountains (Lower Saxony to Saxony-Anhalt) and found in the Ore Mountains (Saxony).
Tsumeb in Namibia is known for its extraordinary azurite finds , where crystals up to 20 centimeters in length came to light. Crystals up to 7 centimeters in size were discovered in Touissit, Morocco, and the crystals in the historic Chessy site near Lyon reached a length of up to 5 centimeters. Crystal rosettes with a diameter of up to 13 centimeters are mainly known from the Yang Chweng mine in the Chinese province of Guangdong .
In Austria, the mineral is mainly known from Carinthia (Friesach-Hüttenberg, Hohe Tauern, Karawanken), Lower Austria (industrial district, Waldviertel) and Salzburg (Hohe Tauern, Leogang), Styria (Fischbacher Alpen, Niedere Tauern, Schladming) and Tyrol ( Inntal, Brixlegg-Schwaz, Kitzbühel Alps).
In Switzerland, azurite was found mainly in the cantons of Graubünden (Albula valley, front and rear Rhine valleys) and Wallis (Binntal, Martigny, Val d'Anniviers).
With the invention of “ Prussian blue ” at the beginning of the 18th century, the mineral lost its importance as a pigment in Europe.
Other locations are in Afghanistan, Argentina, Australia, Bolivia, Brazil, Bulgaria, Chile, China, Democratic Republic of the Congo (Zaire), Greece, Iran, Ireland, Japan, Kazakhstan, Canada, Madagascar, Morocco, Mexico, Mongolia, Namibia , Norway, Peru, Philippines, Poland, Portugal, Russia, Sweden , Switzerland , Serbia , Zimbabwe , Slovakia, South Africa, Czech Republic, Turkey, Hungary, the United Kingdom (UK) and the United States of America (USA).
use
Azurite is a copper ore that is not of great economic importance. However, it can already be proven as a gemstone and color pigment in ancient Egypt . Because of its noble, deep blue color and its high price, azurite was used especially in artistically painted medieval manuscripts.
Manipulations and imitations
Since azurite is too soft and sensitive (porous, easy to split) for commercial use as a gem stone , it is often stabilized with plastic, which also increases the gloss. Reconstructions from azurite and malachite dust (processing residues), especially to imitate the azurite-malachite intergrowth, are also known. Since 1991 an azurite-malachite imitation made of colored barite powder compressed with plastic under high pressure has been in circulation.
Esoteric
In esoteric circles , azurite is considered a stone of knowledge and spiritual growth. It is supposed to promote the ability to concentrate and the mental readiness to take in, have a positive influence on the central nervous system by increasing the efficiency of the brain and nerve activity and stimulating the sensory perception. In addition, the mineral is said to have a detoxifying effect on the organism, stimulate the thyroid functions and support the regeneration of the body after operations or illnesses. However, there is no scientific evidence for the area of action in esotericism.
See also
literature
- Robert Jameson: System of Mineralogy . tape 2 . Bell and Bradfute, Edinburgh 1805, pp. 542–544 ( rruff.info [PDF; 129 kB ; accessed on March 31, 2018]).
- FS Beudant: Traité Élémentaire de Minéralogie . 2nd Edition. Chez Verdière, Libraire-Éditeur, Paris 1832, p. 373–374 ( rruff.info [PDF; 298 kB ; accessed on March 31, 2018]).
- Walter Schumann: Precious stones and gemstones. All kinds and varieties. 1900 unique pieces . 16th revised edition. BLV Verlag, Munich 2014, ISBN 978-3-8354-1171-5 , pp. 190 .
Web links
- Mineral Atlas: Azurite and Mineral Portrait Azurite (Wiki)
- Gemstone Database - Azurite
- RRUFF Database-of-Raman-spectroscopy - Azurite (English)
- American-Mineralogist-Crystal-Structure-Database - Azurite (English)
Individual evidence
- ↑ Webmineral - Azurite (English)
- ^ A b c 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. 293 .
- ↑ a b c Azurite . 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; 66 kB ; accessed on March 31, 2018]).
- ↑ a b c d e Mindat - Azurite (English)
- ↑ Kremer Pigments - Azurit (mountain blue, basic copper carbonate blue, Pigment Blue 30)
- ↑ 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. 180 .
- ^ A b Helmut Schrätze , Karl-Ludwig Weiner : Mineralogie. A textbook on a systematic basis . de Gruyter, Berlin; New York 1981, ISBN 3-11-006823-0 , pp. 544 .
- ^ Helmut Schrätze , Karl-Ludwig Weiner : Mineralogie. A textbook on a systematic basis . de Gruyter, Berlin; New York 1981, ISBN 3-11-006823-0 , pp. 164 .
- ↑ Mindat - Number of localities for azurite
- ↑ Petr Korbel, Milan Novák: Mineral Encyclopedia (= Dörfler Natur ). Nebel Verlag, Eggolsheim 2002, ISBN 978-3-89555-076-8 , p. 122 .
- ↑ Find location list for azurite in the Mineralienatlas and Mindat
- ↑ Bernhard brother embellished stones. Recognizing imitations and manipulations in gemstones and minerals . Neue Erde Verlag, 2005, ISBN 978-3-89060-079-6 , pp. 48 .