Rhodochrosite
| Rhodochrosite | |
|---|---|
 |
|
| General and classification | |
| other names |
|
| chemical formula | Mn [CO 3 ] |
|
Mineral class (and possibly department) |
Carbonates (and relatives) |
|
System no. to Strunz and to Dana |
5.AB.05 ( 8th edition : V / B.02) 01/14/01/04 |
| Similar minerals | Dolomite , fire opal , rhodonite , rose quartz |
| Crystallographic Data | |
| Crystal system | trigonal |
| Crystal class ; symbol | ditrigonal-scalenohedral 3 2 / m |
| Space group | R 3 c (No. 167) |
| Lattice parameters | a = 4.77 Å ; c = 15.63 Å |
| Formula units | Z = 6 |
| Twinning | after {01 1 2} |
| Physical Properties | |
| Mohs hardness | 3.5 to 4.5 |
| Density (g / cm 3 ) | 3.3 to 3.6 |
| Cleavage | completely according to {10 1 1} |
| Break ; Tenacity | shell-like |
| colour | Pink-red to gray-brown, white, yellow, black outer crust |
| Line color | White |
| transparency | transparent to opaque |
| shine | Glass luster, gap surface has pearlescent luster |
| Crystal optics | |
| Refractive indices |
n ω = 1.814 to 1.816 n ε = 1.596 to 1.598 |
| Birefringence | δ = 0.218 |
| Optical character | uniaxial negative |
| Other properties | |
| Chemical behavior | soluble in warm acids, turns brown in the flame, does not melt |
Rhodochrosite , also outdated as manganese spar , incar rose , rose spar or raspberry spar , is a frequently occurring mineral from the mineral class " carbonates and nitrates " (formerly carbonates, nitrates and borates). It crystallizes in the trigonal crystal system with the composition Mn [CO 3 ], so it is chemically a manganese carbonate .
Rhodochrosite usually develops rhombohedral or scalenohedral crystals , but also spherical or grape-like and granular to massive aggregates of pink to red or brown, rarely white color with white streak color . Often rhodochrosite occurs banded concentrically and with black, crusty coatings or in the form of contact twins . In addition, it forms various pseudomorphoses , including after mussels.
With a Mohs hardness of 3.5 to 4.5, rhodochrosite ranks between the soft and medium-hard minerals and can be easily scratched with a knife. Nevertheless, it is often used as a gemstone due to its usually strong rose-red to raspberry-red color and its lively glass shine or due to its striking bands .
Etymology and history
Abraham Gottlob Werner (1749–1817) initially named the mineral manganese spar due to its chemical composition and its good cleavage properties .
By Friedrich Haussmann (1782-1859) it received in 1813 the final name of "Rhodochrosite". This is derived from the ancient Greek language , whereby the first component of the word - "Rhodo-" - occurs there in the Attic dialect as ῥόδον [rʰódon] or in the Aiolic dialect βρόδον [brʰódon] "Rose (nduft)" and already in Mycenaean Greek as <wo-do-we> / u̯rodóu̯en / "das Rosige / Rosenduftige" is occupied. Using the Armenian “vard” and Latin “rosa”, it finally went over to the German word “ rose ”. The second component "-chrosit" can be on χρῶμα [kʰrʰɔːma] "(sound) color, colorants" or χρώς [kʰrʰɔːs] traced "skin (skin) color".
Later August Breithaupt (1791–1873) suggested the alternative names Rosenspat and Raspberry Spat , as he considered the name Rhodochrosite to be foul-sounding and difficult to pronounce.
The " Cavnic Mine" in Romania is considered to be the type locality for the rhodochrosite .
classification
In the now outdated, but still in use 8th edition of the mineral classification according to Strunz , the rhodochrosite belonged to the common mineral class of "carbonates, nitrates and borates " and there to the department of "anhydrous carbonates without foreign anions ", where together with calcite , gaspéit , Magnesite , otavite , siderite , smithsonite , spherocobaltite and vaterite the "calcite group" with the system no. V / B.02 formed.
The 9th edition of Strunz's mineral systematics , which has been valid since 2001 and is used by the International Mineralogical Association (IMA), assigns rhodochrosite to the class of "carbonates and nitrates" (the borates form a separate class here) and there into the department of " Carbonates without additional anions; without H 2 O “. However, this section is further subdivided according to the type of cations involved , so that the mineral can be found according to its composition in the sub-section "alkaline earth (and other M 2+ ) carbonates", where it is found together with calcite, gaspéit, magnesite, otavite , Siderite, smithsonite and spherocobaltite the "calcite group" with the system no. 5.AB.05 forms.
The systematics of minerals according to Dana assigns the rhodochrosite like the outdated 8th edition of Strunz's systematics in the common class of "carbonates, nitrates and borates" and there in the department of "anhydrous carbonates". Here it is together with calcite, magnesite, siderite, spherocobaltite, smithsonite, otavite and gaspéit in the "calcite group (trigonal: R-3c)" with the system no. 01/14/01 to be found in the subsection of " Anhydrous carbonates with simple formula A + CO 3 ".
Crystal structure
Rhodochrosite crystallizes isotypically with calcite trigonal in the space group R 3 c (space group no. 167) with the lattice parameters a = 4.77 Å and c = 15.63 Å as well as 6 formula units per unit cell .
properties
Rhodochrosite is easily soluble in warm acids and disintegrates ( dissociates ) at around 650 ° C.
Rhodochrosite, which fluoresce pink-violet under UV light , are also rarely found .
Education and Locations
Rhodochrosite forms as a primary mineral in medium- to low-grade hydrothermal - veins , where it mostly in paragenesis with Barite , calcite , dolomite , fluorite , Hübnerit , pyrite , quartz , siderite , sphalerite and tetrahedrite is found; or in some metamorphic rocks of sedimentary origin mostly together with alabandin , garnet , hausmannite and rhodonite .
The classical banding arises similar to lime - stalactites by the influence of water and the resulting layers of the deposit for dissolved mineral. The fluctuating mineral concentration of the water forms different layers of deposits and thus the characteristic pattern.
So far (as of 2011) rhodochrosite has been found at around 1400 sites worldwide. In addition to its type locality "Cavnic Mine", which is also known for its pink-colored, spherical to kidney-shaped aggregates, the mineral was found in Romania in a few other places in the Maramureş district as well as at Baia de Arieş and Roşia Montană in the Alba district and at Suceava in eponymous circle.
The “Sweet Home Mine” near Alma (Colorado) , in which rhombohedral crystals up to 15 cm in size, are worth mentioning due to their significant rhodochrosite finds, is among others . Up to 10 cm large, scalenohedral and deep red crystals were found in the South African N'Chwaning Mines 1 and 2 near Kuruman and about 8 cm large rhodochrosite rhombi were found in Silverton (Colorado) . The location of beautiful crystals of the mineral was also found in the Wolf pit in Siegerland and smaller ore mines in the Rheingau (Geisenheim) and near Bingen (Waldalgesheim) in Germany.
Important deposits of the mineral are in Butte in the US state of Montana , where the mineral is mined as manganese ore, in Colorado , another state in the USA, in Mexico , Argentina , Brazil , the African states of Gabon and South Africa as well as in Romania , Russia and Japan .
Other locations are Afghanistan , Armenia , Australia , Belgium , Bolivia , Bosnia and Herzegovina , Brazil , Bulgaria , Chile , China , Ecuador , Finland , France , Gabon , Georgia , Ghana , Greece , Greenland , Honduras , India , Indonesia , Ireland , Isle of Man , Italy , Japan , Canada , Kazakhstan , Kyrgyzstan , Kosovo , Mexico , Mongolia , Namibia , New Caledonia , New Zealand , North Macedonia , Norway , Austria , Papua New Guinea , Peru , Philippines , Poland , Portugal , Russia , Saudi Arabia , Slovakia , Sweden , Switzerland , Spain , South Korea , Taiwan , Czech Republic , Turkey , Ukraine , Hungary , the United Kingdom (Great Britain) and the United States of America .
Also in rock samples from the seabed of the Baltic Sea (English Baltic Sea ) near the island Gotland depth Gotland were taken in the so-called, rhodochrosite could (in addition rambergite be detected).
use
As a raw material
Due to its high manganese content of up to 47.8%, rhodochrosite serves as an important manganese ore .
As a gem
Rhodochrosite has also been used as a gemstone since the 1950s . Clear gem-quality rhodochrosite crystals are rarely found. Since the pink white banded units, however, are drawn similarly striking how different agates and Rhodonit , the too pleased jewelry or crafts objects processed Rhodochrosit increasing popularity. Raspberry-red colored gemstones are particularly popular .
In order to better accentuate the banding and drawing of the stone, the cabochon cut and the use of larger pieces are preferred.
Depending on which color the clear or banded varieties of rhodochrosite take on, they can be confused with various other minerals, including fire opal , rhodonite, rose quartz , tugtupite and tourmaline .
See also
literature
- Paul Ramdohr , Hugo Strunz : Klockmann's textbook of mineralogy . 16th edition. Ferdinand Enke Verlag, 1978, ISBN 3-432-82986-8 , pp. 571 .
- Petr Korbel, Milan Novák: Encyclopedia of Minerals . Nebel Verlag GmbH, Eggolsheim 2002, ISBN 3-89555-076-0 , p. 115 .
- Walter Schumann: Precious stones and gemstones. All species and varieties in the world. 1600 unique pieces . 13th revised and expanded edition. BLV Verlags GmbH, Munich et al. 2002, ISBN 3-405-16332-3 , p. 184 .
Web links
- Mineral Atlas: Rhodochrosite and Mineralienatlas: Mineralienportrait / Rhodochrosite (Wiki)
- realgems.org - Rhodochrosite (with many picture examples of cut rhodochrosite)
Individual evidence
- ^ A b c Hugo Strunz , Ernest H. Nickel: Strunz Mineralogical Tables . 9th edition. E. Schweizerbart'sche Verlagbuchhandlung (Nägele and Obermiller), Stuttgart 2001, ISBN 3-510-65188-X , p. 286 .
- ↑ a b Mindat - Rhodochrosite (English)
- ↑ For examples of pseudomorphoses according to Muschel, see Commons: File: Rhodochrosite-54300.jpg and Commons: Category: Pseudomorph
- ↑ Gotland Deep mineral site, Baltic Sea ; Original source: John L. Jambor, Vladimir A. Kovalenker, Andrew C. Roberts: New Mineral Names. Rambergite In: American Mineralogist Volume 83, 1998, pp. 1117–1121 ( PDF 70.6 kB )
- ↑ Webmineral - Rhodochrosite (English)
- ^ Walter Schumann: Precious stones and gemstones. All species and varieties in the world. 1600 unique pieces . 13th revised and expanded edition. BLV Verlags GmbH, Munich et al. 2002, ISBN 3-405-16332-3 , p. 184 .
