Struvite
- Ammonium magnesium phosphate
Struvite is a rarely occurring mineral from the mineral class of " phosphates, arsenates and vanadates ." It crystallizes in the orthorhombic crystal system with the composition ( NH4) Mg [ PO4 ] · 6H2O, is thus seen chemically a hydrous magnesium ammonium phosphate.
Struvite usually develops colorless and transparent, hemimorphic crystals with isometric, wedge-shaped or short prismatic habit to tafeligem to about three centimeters in size. By crystal defects or multiple twinning struvite can look white and accept by foreign admixtures a brown color.
Special Features
Ammonium magnesium phosphate is one of the most sparingly soluble compounds of ammonium and magnesium. In the long, coffin-shaped crystal form of Struvits this connection is so characteristic that it is used in the classical analytical separation process for the detection of magnesium.
In warm, dry air, the crystal faces of struvite run at the time by dehydration to know.
Struvite is pyroelectric and piezoelectric, so it can build by interval -like heat change and deformation of electrical shock.
Etymology and history
Struvite was first found in Hamburg in 1846 during archaeological excavations under the church of St. Nicholas and described by Georg Ludwig Ulex, who named the mineral after the naturalist and diplomat Heinrich von Struve ( 1772-1851 ).
Type material of the mineral is including in the Mineralogical Museum of the University of Hamburg.
Classification
In the now outdated but still in use 8th edition of the mineral classification by Strunz of struvite belonged to the mineral class of " phosphates, arsenates and vanadates " and then to the Department of " water -containing phosphates without foreign anions ", where he along with Dittmarit, Hannayit, Mundrabillait, Niahit, Schertelit, Stercorit, struvite -K and Swaknoit the unnamed group VII/C.23 formed.
The valid since 2001 and used by the IMA 9th edition of the Strunz'schen Mineral classification assigns the struvite also in the department of " water -containing phosphates without foreign anions " one. This division, however, is further divided according to the size of the involved cations and the anion RO 4 relative to H2O. The mineral is thus "With large and medium-sized cations, RO 4: H 2 O <1: 1" according to its composition in the subdivision to find where it forms the unnamed group 8.CH.40 together with Hazenit and struvite -K.
The classification of minerals according to Dana assigns the struvite also in the class of " phosphates, arsenates and vanadates " and then in the Department of " Water-containing phosphates, etc. " field. There he is with Hazenit and struvite - K in the eponymous " Struvitgruppe " with the system no. 40.01.01 within the subdivision " water containing phosphates, etc., with A2 B2 ( XO4 ) × x (H2O) " sorted.
Education and Locations
Struvite forms in nature usually in peaty, with cattle manure or bird or bat droppings mixed earth in surface deposits or den floors. There in paragenesis occurs among other Newberyit, Hannayit, brushite and Stercorit.
Worldwide, struvite far (as of 2010) are detected in about 45 localities, as in some regions of Victoria and Tasmania in Australia; in the Gcwihaba Cave near Maun in Botswana; in some regions of the Canadian provinces of Yukon, Quebec, Newfoundland and Labrador; at Aalborg in Denmark; in the Falkland Islands; in Germany in addition to its type locality St. Nikolai (Hamburg) nor in Bad Homburg ( Hesse) and Lüneburg ( Lower Saxony ); at Trepča in Kosovo; in the Malaysian state of Sarawak; on Ichaboe Iceland in Namibia; in the Netherlands Amsterdam; on Reunion Island in the Indian Ocean; on the beach of the island Hoedjes Saldanha in the Western Cape of South Africa; in the U.S. regions Colorado, California and Maine, as well as in the state of Miranda ( Venezuela).
Furthermore, struvite can also form in wastewater treatment and during slurry preparation. In places, this produces such high concentrations of ammonium, magnesium and phosphate that the saturation concentration of struvite is exceeded. Then coverings made of struvite, which may affect the operation of sewage or manure treatment systems form.
Biological Significance
In medicine struvite is known as a material of kidney and urinary stones. Approximately eleven percent of kidney stones in humans are " struvite stones ," and the most common type of kidney stones in children ( about 93 %). They are formed in alkaline urine. Cause of alkalinization are bacteria - especially Proteus mirabilis - mostly due to pyelonephritis ( kidney infection ) due to an ascending urinary tract infection. Uric acid is the starting material which is broken down by bacteria to ammonia.
Among the domestic animals are affected by struvite stones particularly common house cats. With them come struvite crystals due to the high pH and high ammonium concentration prior without infections.
Crystal structure
Struvite crystallizes isostructural with struvite - (K ) in the orthorhombic crystal system, space group Pmn21 ( Raumgruppen-Nr. 31) with the lattice parameters a = 6.95 Å; b = 6.14 Å; c = 11.22 Å and two formula units per unit cell.