Portlandite
Portlandite ( chemically: calcium hydroxide, slaked lime) is a very rare 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 usually develops colorless to greenish white, fibrous, powdery and bulky mineral aggregates, but also hexagonal tabular crystals to about 6 cm in size.
Etymology and history
Was first found in 1933 Portlandite Scawt Hill in England and described by Cecil Edgar Tilley ( 1894-1973 ), who named the mineral based on its similarity of the synthetic product Portland cement.
Classification
In the now outdated but still in use 8th edition of the mineral classification by Strunz the portlandite belonged to the department of " hydroxides and oxide hydrates ( hydrous oxides with layered structure ) ", where he, along with Amakinit, Ashoverit, brucite, Paraotwayit, Pyrochroit, Spertiniit Sweetit, Theophrastit and Wülfingit " brucite - series" with the system no. IV/F.03 formed.
The 9th edition valid since 2001 and of the International Mineralogical Association (IMA ) used the Strunz'schen Mineral classification leads to portlandite under the Department " Hydroxide (without V or U) " and then in the sub-division of " hydroxides with OH, without H2O; with layers of edge-sharing octahedra, "where he along with Amakinit, brucite, Fougèrit, Pyrochroit and Theophrastit the ". brucite - group "with the System No. 4.FE.05 forms.
The commonly used in English-speaking classification of minerals according to Dana assigns the portlandite in the department of " hydroxides and hydroxy- oxides " and then in the sub-division of " hydroxides and hydroxy- oxides with the formula X2 ( OH) 2 ." Again, the mineral is in the " Brucitgruppe ( rhombohedral: P 3 m 1 ) " with the system number. 06:02:01 and the other members Amakinit, brucite, Pyrochroit and find Theophrastit.
Education and Locations
Portlandite has different ways of natural history. As a conversion product of calcium silicates in larnit and spurrithaltigen, contact metamorphic rocks, it was among other things in Scawt Hill in Ireland or fumaroles on Vesuvius. In Jebel AWQ in Oman to portlandite formed by deposition from alkaline sources in ultramafic rocks. In Russia, the mineral could be found in burning coal dumps at Chelyabinsk and in the Hatrurim formation in Israel and in the region of the Jordan Maqarin to portlandite also formed in metamorphic sedimentary deposits by spontaneous combustion of the bitumen contained. Accompanying minerals are sorted by locality Afwillit, brownmillerite, calcite, ettringite, halite, hydrocalumite, Larnit, mayenite and spurrite.
Other localities include Australia ( Lake Boga ); Belgium ( Saint- Jean); Germany ( Zeilberg, Fire Mountain, Emmelberg, Bellerberg, Lichtenberg); France ( Boisséjour, Lapanouse -de- Sévérac ); Italy ( Campomorto, Carpenara ); Mexico ( Cerro de la Coronita ); Norway ( Kongsberg ); Palestine ( Ma'aleh Adumim ); Poland ( Dabrówka Wielka ); Romania ( Cornet Hill ); South Africa ( Blackrock, Hotazel , Kuruman ); Tunisia ( Jebel Sekarna ); Hungary ( Kányáspuszta ); the United Kingdom ( Carneal ) and in the United States ( Virginia).
Crystal structure
Portlandite trigonal crystallized in the space group P3m1 ( Raumgruppen-Nr. 164) with the lattice parameters a = 3.59 Å and c = 4.91 Å, and one formula unit per unit cell.