Hagendorfite is an

iron Iron () is a chemical element with symbol Fe (from la, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, right in f ...

phosphate mineral Phosphate minerals contain the tetrahedrally coordinated phosphate (PO43−) anion along sometimes with arsenate (AsO43−) and vanadate (VO43−) substitutions, and chloride (Cl−), fluoride (F−), and hydroxide (OH−) anions that also fit i ...

with the chemical formula of and is named after where the mineral was discovered, Hagendorf-Süd,

Bavaria Bavaria ( ; ), officially the Free State of Bavaria (german: Freistaat Bayern, link=no ), is a state in the south-east of Germany. With an area of , Bavaria is the largest German state by land area, comprising roughly a fifth of the total lan ...

Germany Germany,, officially the Federal Republic of Germany, is a country in Central Europe. It is the second most populous country in Europe after Russia, and the most populous member state of the European Union. Germany is situated betwe ...

. Hagendorfite is in the monoclinic crystal class; the mineral's internal symmetry consists of three axes with unequal length. Furthermore, the angles between two of the axes is 90° while the other angle is less than 90°. Monoclinic minerals contain a twofold rotation axis where they can be rotated 360° and have the crystal face repeat every 180°. They also have the characteristic mirror plane, which can produce a perfect mirror image when divided in two. Hagendorfite belongs to the monoclinic crystal class, so it is assigned to the biaxial optical class. Hagendorfite's optic sign, which is negative, is proven by examining its interference figure. Biaxial minerals, including Hagendorfite, have three indices of refraction which may or may not correspond with the mineral's unequally lengthened axes. A refractive index will provide the ratio of the speed of light in vacuum with the speed of light in the mineral. A single refractive index is given when two rays of light vibrate in the mineral's circular section and move along the optic axes.

Occurrence

The mineral is found in various locations around the world. Hagendorfite occurs in complex

granite Granite () is a coarse-grained (phaneritic) intrusive igneous rock composed mostly of quartz, alkali feldspar, and plagioclase. It forms from magma with a high content of silica and alkali metal oxides that slowly cools and solidifies undergro ...

course-grained rocks called

pegmatites A pegmatite is an igneous rock showing a very coarse texture, with large interlocking crystals usually greater in size than and sometimes greater than . Most pegmatites are composed of quartz, feldspar, and mica, having a similar silicic comp ...

or in the

phosphate nodule Phosphorite, phosphate rock or rock phosphate is a non-detrital sedimentary rock that contains high amounts of phosphate minerals. The phosphate content of phosphorite (or grade of phosphate rock) varies greatly, from 4% to 20% phosphorus pentoxi ...

s in

shale Shale is a fine-grained, clastic sedimentary rock formed from mud that is a mix of flakes of clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2 Si2 O5( OH)4) and tiny fragments (silt-sized particles) of other minerals, especial ...

. Although hagendorfite was first discovered in Bavaria, Germany, it has since been found in the Southern Province in

Rwanda Rwanda (; rw, u Rwanda ), officially the Republic of Rwanda, is a landlocked country in the Great Rift Valley of Central Africa, where the African Great Lakes region and Southeast Africa converge. Located a few degrees south of the Equator ...

, the Sowie Mountains in

Poland Poland, officially the Republic of Poland, is a country in Central Europe. It is divided into 16 administrative provinces called voivodeships, covering an area of . Poland has a population of over 38 million and is the fifth-most populous ...

, and

New Hampshire New Hampshire is a U.S. state, state in the New England region of the northeastern United States. It is bordered by Massachusetts to the south, Vermont to the west, Maine and the Gulf of Maine to the east, and the Canadian province of Quebec t ...

in the US.Moore P. (1965) Huhnerkobelite Crystals from the Palermo No. 1 Pegmatite, North Groton, New Hampshire. American Mineralogist, 50, 713-717. Hagendorfite is of interest to mineralogists researching phosphate-bearing pegmatites or the dickinsonite series. Hagendorfite is associated with the dickinsonite series and with other mineral members including varulite, alluarrdite, and manganalluaudite.

References

{{reflist Phosphate minerals Monoclinic minerals Minerals in space group 15