Portlandite
| Portlandite | |
|---|---|
 |
|
| General and classification | |
| chemical formula | Ca (OH) 2 |
|
Mineral class (and possibly department) |
Oxides and hydroxides |
|
System no. to Strunz and to Dana |
4.FE.05 ( 8th edition : IV / F.03) 02/06/01/04 |
| Crystallographic Data | |
| Crystal system | trigonal |
| Crystal class ; symbol | ditrigonal-scalenohedral; 3 2 / m |
| Space group | P 3 m 1 (No. 164) |
| Lattice parameters | a = 3.59 Å ; c = 4.91 Å |
| Formula units | Z = 1 |
| Physical Properties | |
| Mohs hardness | 2 |
| Density (g / cm 3 ) | measured: 2.23; calculated: 2.26 (synthetic) |
| Cleavage | completely after {0001} |
| Break ; Tenacity | flexible, cuttable |
| colour | colorless, white to greenish white |
| Line color | White |
| transparency | transparent |
| shine | Pearl luster on cleavage surfaces |
| Crystal optics | |
| Refractive indices |
n ω = 1.574 n ε = 1.547 |
| Birefringence | δ = 0.027 |
| Optical character | uniaxial negative |
| Other properties | |
| Chemical behavior | soluble in H 2 O, forming alkaline solution; on contact with water containing CO 2 it is converted into calcium carbonate |
Portlandite (chemical: calcium hydroxide , slaked lime ) is a very rarely occurring mineral from the mineral class of " oxides and hydroxides ". It crystallizes in the trigonal crystal system with the chemical composition Ca (OH) 2 and develops mostly colorless to greenish white, fibrous, powdery to massive mineral aggregates , but also hexagonal, tabular crystals up to about 6 cm in size.
Etymology and history
Portlandite was first found in 1933 Scawt Hill in England and described by Cecil Edgar Tilley (1894–1973), who named the mineral because of its similarity to the synthetic product Portland cement .
Type material of the mineral is in the Natural History Museum in London under the inventory no. 1933,307 kept.
classification
In the now outdated, but still in use 8th edition of the mineral classification according to Strunz , portlandite belonged to the division of "hydroxides and oxidic hydrates (water-containing oxides with a layer structure)", where together with amakinite , ashoverite , brucite , paraotwayite , pyrochroitite , spertiniite , Sweetite , Theophrastit and Wülfingit "Brucit-range" with the system no. IV / F.03 .
The 9th edition of Strunz's mineral systematics , which has been in force since 2001 and is used by the International Mineralogical Association (IMA), lists portlandite under the section "Hydroxides (without V or U )" and there in the sub-section of "Hydroxides with OH, without H 2 O; with layers of edge-linked octahedra ", where together with amakinite, brucite, fougèrite , pyrochroit and theophrastite, the" brucite group "with the system no. 4.FE.05 forms.
The systematics of minerals according to Dana , which is common in the English-speaking world , assigns portlandite to the "hydroxides and hydroxyl- containing oxides" section and there in the " hydroxides and hydroxyl-containing oxides with the formula X 2+ (OH) 2 " sub-section . Here, too, the mineral is in the "brucite group (rhombohedral: P 3 m 1 )" with the system no. 06.02.01 and the other members amakinite, brucite, pyrochroit and theophrastite.
Crystal structure
Portlandite crystallizes trigonal in the space group P 3 m 1 (space group no.164) with the lattice parameters a = 3.59 Å and c = 4.91 Å and one formula unit per unit cell .
Education and Locations
Portlandite has different possibilities of natural formation. As a conversion product of calcium - silicates in Larnite - and spurrithaltigen , kontaktmetamorphen rocks emerged, among other things in Scawt Hill in Ireland or fumaroles on Vesuvius . In Jebel Awq , Oman , portlandite was formed by deposition from alkaline sources in ultramafic rocks . In Russia, the mineral was found in burning coal heaps near Chelyabinsk and in the Hatrurim Formation in Israel and in the Maqarin area on the Jordan , portlandite also formed metamorphically in sedimentary deposits after spontaneous combustion of the bitumen it contained . Accompanying minerals are sorted by location Afwillit , brownmillerite , calcite , ettringite , halite , hydrocalumite , Larnite, Fluormayenit , Chlormayenit and spurrite.
Other locations include Australia (Lake Boga); Belgium (Saint-Jean); Germany (Zeilberg, Feuerberg, Emmelberg, Bellerberg, Lichtenberg); France (Boisséjour, Lapanouse-de-Sévérac); Italy (Campomorto, Carpenara); Mexico (Cerro de la Coronita); Norway (Kongsberg); Palestine (Ma'aleh Adumim); Poland (Dąbrowka Wielka); Romania (Cornet Hill); South Africa (Black Rock, Hotazel, Kuruman); Tunisia (Djebel Sekarna); Hungary (Kányáspuszta); in the United Kingdom (Carneal) and in the United States (Virginia).
See also
literature
- Helmut Schrätze , Karl-Ludwig Weiner : Mineralogy. A textbook on a systematic basis . de Gruyter, Berlin; New York 1981, ISBN 3-11-006823-0 , pp. 484 .
- 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. 424 .
Web links
- Mineral Atlas: Portlandite (Wiki)
Individual evidence
- ↑ Webmineral - Portlandite (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. 237 .
- ↑ a b c d Portlandite . 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; 68 kB ; accessed on October 28, 2017]).
- ↑ a b c d Mindat - Portlandite (English)
- ↑ GA Chinner: Memoriaol of Cecil Edgar Tilley. May 14, 1894 - January 24, 1973 . In: American Mineralogist . tape 59 , 1974, pp. 427–437 ( minsocam.org [PDF; 1,3 MB ; accessed on October 28, 2017]). [] (English, 1.2 MB)