Syngenite
| Syngenite | |
|---|---|
 |
|
| General and classification | |
| other names |
|
| chemical formula | K 2 Ca [SO 4 ] 2 • H 2 O |
|
Mineral class (and possibly department) |
Sulfates (including selenates, tellurates, chromates, molybdates, and tungstates) |
|
System no. to Strunz and to Dana |
7.CD.35 ( 8th edition : VI / C.21) 03/29/01/01 |
| Crystallographic Data | |
| Crystal system | monoclinic |
| Crystal class ; symbol | monoclinic prismatic; 2 / m |
| Space group | P 2 1 / m (No. 11) |
| Lattice parameters |
a = 9.77 Å ; b = 7.15 Å; c = 6.25 Å β = 104.0 ° |
| Formula units | Z = 2 |
| Twinning | Contact twins after {100} |
| Physical Properties | |
| Mohs hardness | 2.5 |
| Density (g / cm 3 ) | 2.579 to 2.603 |
| Cleavage | shell-like |
| Break ; Tenacity | completely according to {110} and {100}; clearly after {010} |
| colour | colorless, white, pale yellow |
| Line color | White |
| transparency | transparent to translucent |
| shine | Glass gloss |
| Crystal optics | |
| Refractive indices |
n α = 1.501 n β = 1.517 n γ = 1.518 |
| Birefringence | δ = 0.017 |
| Optical character | biaxial negative |
| Axis angle | 2V = 28 ° |
Syngenite is a rather seldom occurring mineral from the mineral class of "sulfates (including selenates, tellurates, chromates, molybdates and tungstates)" with the chemical composition K 2 Ca [SO 4 ] 2 · H 2 O and is therefore chemically a water-containing potassium - calcium - sulphate .
Syngenite crystallizes in the monoclinic crystal system and develops in nature mostly tabular to prismatic crystals , but also lamellar mineral aggregates and crusty coatings that are either colorless to white or pale yellow in color due to foreign admixtures.
Syngenite is isotypic with coktaite , which means that both minerals crystallize in the same crystal structure .
Etymology and history
Syngenite was first discovered in the salt deposit near Kalusch ( Kalusa , Kalusz ) in the Ukraine . It was first described in 1872, curiously and independently of one another, on the one hand by Victor Leopold Ritter von Zepharovich , who named the mineral after the Greek word συγγευής for "related" due to its chemical similarity to polyhalite and on the other hand by Johann Rumpf , who named it after its type locality called Kaluszite (or Kalushite ). For a long time, both names were used equally, until the name Syngenit finally caught on.
classification
In the outdated, but partly still in use 8th edition of the mineral classification according to Strunz , the syngenite belonged to the mineral class of "sulfates, chromates, molybdates, wolframates" (including selenates and tellurates) and there to the department "C. Water-containing sulfates, without foreign anions ”, where, together with Mirabilit, he named the“ Mirabilit-Syngenit Group ”with the system no. VI / C.21 and the other members Eugsterit , Hydroglauberit , Koktait , Lecontit , Matteuccit and Wattevillit formed.
The 9th edition of Strunz's mineral systematics, valid since 2001 and used by the International Mineralogical Association (IMA), also assigns syngenite to the class of "sulfates (selenates, tellurates, chromates, molybdates and wolframates)" and there in the department of "Sulphates (selenates etc.) without additional anions, with H 2 O". This is, however, further subdivided according to the relative size of the cations involved , so that the mineral can be found according to its composition in the subsection “With only large cations”, where it only forms the unnamed group 7.CD.35 together with Koktaite .
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns syngenite to the class of "sulfates, chromates, molybdates" and there in the category of "water-containing acids and sulfates". Here it can also be found together with Koktait in the unnamed group 29.03.01 within the subdivision " Water-based acids and sulfates with (A + ) 2 B (XO 4 ) 2 × x (H 2 O) ".
Crystal structure
Syngenite crystallizes in the monoclinic crystal system in the space group P 2 1 / m (space group no. 11) with the lattice parameters a = 9.77 Å ; b = 7.15 Å, c = 6.25 Å and β = 104.0 ° as well as two formula units per unit cell .
Education and Locations
Syngenite is formed in nature either diagenetically in oceanic salt deposits or as a pneumatolytic resublimation product or as a hydrothermal vein filling through volcanic activity. Accompanying minerals are mainly aphthitalite , arcanite , biphosphammite , brushite , gypsum , halite , monetite , uricite and whitlockite .
So far (as of 2018) around 40 sites have been documented for Syngenit worldwide: Eucla and Madura in Australia; near Maun in Botswana ; Hubei in China; in the Werra Valley (Hesse), near Celle , Hanover and Lüneburg (Lower Saxony), Tarthun (Saxony-Anhalt), Gera and Sondershausen (Thuringia) in Germany; Aveyron in France; on Vesuvius in Italy; Hallstatt in Austria; at Rodna in Romania; in addition to its type locality Kalusch, in Drohobych in the Ukraine; as well as on Maui , in Esmeralda County and Eddy County (New Mexico) in the USA.
Syngenit can also be synthetically precipitated from the cement solution within a few minutes during concreting due to an excessive supply of potassium sulfate or a lack of water . The resulting crystals bind the cement particles and cause the concrete to set prematurely. Although the syngenite is reacted again in the course of hydration, its formation does pose a problem for the processing of the fresh concrete.
See also
literature
- VR v. Zepharovich: Preliminary note on syngenite, a new mineral from the salt deposits, lotus . In: Journal of Natural Sciences . tape 22 , 1872, p. 137–138 ( rruff.info [PDF; 616 kB ; accessed on April 14, 2018]).
- Johann Rumpf: About Kaluszite, a new mineral from Kalusz . In: G. Tschermak (Hrsg.): Mineralogische Mittheilungen . tape 3 , 1872 ( PDF on ZOBODAT [accessed April 14, 2018]).
- E. Corazza, C. Sabelli: The structure of syngenite, K 2 Ca (SO 4 ) 2 · H 2 O . In: Journal of Crystallography . tape 124 , 1967, pp. 398-408 ( rruff.info [PDF; 537 kB ; accessed on April 14, 2018]).
- Friedrich Klockmann : Klockmann's textbook of mineralogy . Ed .: Paul Ramdohr , Hugo Strunz . 16th edition. Enke, Stuttgart 1978, ISBN 3-432-82986-8 , pp. 611 (first edition: 1891).
Web links
- Mineral Atlas: Syngenite (Wiki)
- RRUFF Database-of-Raman-spectroscopy - Syngenite (English)
- American Mineralogist Crystal Structure Database - Syngenite (English)
Individual evidence
- ^ A b Igor V. Pekov: Minerals first discovered on the territory of the former Soviet Union . 1st edition. Ocean Pictures, Moscow 1998, ISBN 5-900395-16-2 , pp. 199-200 .
- ↑ Johann Rumpf: About Kaluszite, a new mineral from Kalusz . In: G. Tschermak (Hrsg.): Mineralogische Mittheilungen . tape 3 , 1872 ( zobodat.at [PDF; 774 kB ; accessed on April 14, 2018]).
- ↑ 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. 393 .
- ↑ Webmineral - Syngenite (English)
- ↑ a b c d e Syngenite at mindat.org (English)
- ↑ Syngenite . 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]).
- ↑ Find location list for syngenite in the Mineralienatlas and Mindat
- ^ Roland Benedix: Construction chemistry. Introduction to chemistry for civil engineers . 3. Edition. Vieweg + Teubner, Wiesbaden 2006, ISBN 978-3-519-20226-4 , pp. 335–336 ( limited preview in Google Book search).