Warikahnite
Encyclopedia
Warikahnite is a rare zinc
arsenate mineral
of the triclinic crystal system with Hermann- Mauguin notation 1*, belonging to the space group P1*. It occurs in the second oxidation zone of the Tsumeb
mine in Namibia
on corroded tennantite
in the second oxidation zone under hydrothermal conditions in a dolostone-hosted polymetallic ore deposit. It is associated with adamite
, stranskiite, koritnigite, claudetite
, tsumcorite
, and ludlockite. The origin of discovery was in a dolostone ore formation within an oxidized hydrothermal zone, in the E9 pillar, 31st level of the Tsumeb Mine in Namibia, Southwest Africa. It has also been found at Lavrion, Greece
and Plaka, Greece
as microscopic white needles.
, the Smithsonian Institution
, and Harvard University
.
data, contained six various coordination polyhedra of zinc with components of As, O, and H₂O; with the coordination numbers six, five, and four; and with five different combinations of ligand. Also noted in the “Die Kristallstruktur von Warikahnit” article, is that the hydrogen bonds are discussed appertaining to both charge balance and infrared spectra. Recent data shows the Gladestone-Dale relation compatibility of Warikahnite is ranked as superior (-0.010).
Zn
3(As
O
4)2•2H2O
. Along with arsenate ions (AsO₄)3-, the infrared spectrum revealed H₂O . These water molecules present in the warikahnite sample were determined by thermo gravimetric analysis, and lost at 365°C. Both H₂O and (AsO₄)3- readily dissolved when hot hydrochloric acid (HCL) or nitric acid (HNO₃) were added to the specimen. After a microprobe analysis, the weight percent oxides were calculated as follows in the table directly below.
, crystals of helmutwinklerite, and white corroded crystals of claudetite
, ludlockite, tsumcorite
, and lavendulan
; while the second acquisition was only linked to quartz
.
Zinc
Zinc , or spelter , is a metallic chemical element; it has the symbol Zn and atomic number 30. It is the first element in group 12 of the periodic table. Zinc is, in some respects, chemically similar to magnesium, because its ion is of similar size and its only common oxidation state is +2...
arsenate mineral
Arsenate mineral
Arsenate minerals usually refer to the naturally occurring orthoarsenates, possessing the 3- anion group and, more rarely, other arsenates with anions like AsO32- or [AsO22]- . Arsenite minerals are much less common...
of the triclinic crystal system with Hermann- Mauguin notation 1*, belonging to the space group P1*. It occurs in the second oxidation zone of the Tsumeb
Tsumeb
Tsumeb is a city of 15,000 inhabitants and the largest town in Oshikoto region in northern Namibia. Tsumeb is the home of the world-famous Tsumeb mine, and the "gateway to the north" of Namibia. It is the closest town to the Etosha National Park...
mine in Namibia
Namibia
Namibia, officially the Republic of Namibia , is a country in southern Africa whose western border is the Atlantic Ocean. It shares land borders with Angola and Zambia to the north, Botswana to the east and South Africa to the south and east. It gained independence from South Africa on 21 March...
on corroded tennantite
Tennantite
Tennantite is a copper arsenic sulfosalt mineral. Its chemical formula is Cu12As4S13. It is grey-black, steel-gray, iron-gray or black in color. A closely related mineral, tetrahedrite has antimony substituting for arsenic and the two form a solid solution series. The two have very similar...
in the second oxidation zone under hydrothermal conditions in a dolostone-hosted polymetallic ore deposit. It is associated with adamite
Adamite
Adamite is a zinc arsenate hydroxide mineral, Zn2AsO4OH. It is a mineral that typically occurs in the oxidized or weathered zone above zinc ore occurrences. Pure adamite is colorless, but usually it possess yellow color due to Fe compounds admixture. Tints of green also occur and are connected with...
, stranskiite, koritnigite, claudetite
Claudetite
Claudetite is an arsenic mineral chemical formula As2O3.It is named for the french chemist, F. Claudet. Claudetite is formed as an oxidation product of arsenic sulfides and is colorless or white. It can be associated with arsenolite as well as realgar, orpiment and sulfur....
, tsumcorite
Tsumcorite
Tsumcorite is a rare hydrated lead arsenate mineral that was discovered in 1971, and reported by Geier, Kautz and Muller. It was named after the TSUMeb CORporation mine at Tsumeb, in Namibia, in recognition of the Corporation’s support for mineralogical investigations of the orebody at its Mineral...
, and ludlockite. The origin of discovery was in a dolostone ore formation within an oxidized hydrothermal zone, in the E9 pillar, 31st level of the Tsumeb Mine in Namibia, Southwest Africa. It has also been found at Lavrion, Greece
Laurium
Laurium or Lavrio is a town in southeastern part of Attica, Greece. It is the seat of the municipality of Lavreotiki...
and Plaka, Greece
Plaka
Pláka is the old historical neighborhood of Athens, clustered around the northern and eastern slopes of the Acropolis, and incorporating labyrinthine streets and neoclassical architecture. Plaka is built on top of the residential areas of the ancient town of Athens...
as microscopic white needles.
Discovery
Warikahnite was discovered by Clive Queit at Tsumeb mine and was first described in 1979 by Keller, Hess, and Dunn. The name "warikahnite" honors Walter Richard Kahn, who was born in 1911. He was from Bayersoien, Germany, and he was a dealer and collector that specialized in Tsumeb minerals. He was honored due to his support of research into rare secondary minerals. The type material is located at the University of StuttgartUniversity of Stuttgart
The University of Stuttgart is a university located in Stuttgart, Germany. It was founded in 1829 and is organized in 10 faculties....
, the Smithsonian Institution
Smithsonian Institution
The Smithsonian Institution is an educational and research institute and associated museum complex, administered and funded by the government of the United States and by funds from its endowment, contributions, and profits from its retail operations, concessions, licensing activities, and magazines...
, and Harvard University
Harvard University
Harvard University is a private Ivy League university located in Cambridge, Massachusetts, United States, established in 1636 by the Massachusetts legislature. Harvard is the oldest institution of higher learning in the United States and the first corporation chartered in the country...
.
Physical properties
Warikahnite pictured in figure two has perfect cleavage on the c-axis {001}; and good cleavage on both the a- and b-axes ({100} and {010}). It has bladed subhedral crystals up to 3 x .5 x .5 mm, elongated on {100} and flattened on {010}, with a hardness of approximately 2 as presented in table two. Its specific gravity is 4.24 and it exhibits a colorless to pale yellow hue, along with a white streak and vitreous luster. This triclinic 1* specimen classified under the space group P1 features striated crystals up to two cm in radial to sub parallel aggregates. The Handbook of Mineralogy further states the cell dimensions of biaxial Warikahnite to be calculated as a = 6.710(1) Å, b = 8.989(2) Å, and c = 14.533(2) Å, with unit cell volume as 788.58 Å; however some physical properties such as appearance are subject to slight change based on locality.Crystal structure
The crystal structure of Warikahnite, determined from diffractometerDiffractometer
A diffractometer is a measuring instrument for analyzing the structure of a material from the scattering pattern produced when a beam of radiation or particles interacts with it....
data, contained six various coordination polyhedra of zinc with components of As, O, and H₂O; with the coordination numbers six, five, and four; and with five different combinations of ligand. Also noted in the “Die Kristallstruktur von Warikahnit” article, is that the hydrogen bonds are discussed appertaining to both charge balance and infrared spectra. Recent data shows the Gladestone-Dale relation compatibility of Warikahnite is ranked as superior (-0.010).
Chemical composition
Warikahnite has the chemical formulaChemical formula
A chemical formula or molecular formula is a way of expressing information about the atoms that constitute a particular chemical compound....
Zn
Zinc
Zinc , or spelter , is a metallic chemical element; it has the symbol Zn and atomic number 30. It is the first element in group 12 of the periodic table. Zinc is, in some respects, chemically similar to magnesium, because its ion is of similar size and its only common oxidation state is +2...
3(As
Arsenic
Arsenic is a chemical element with the symbol As, atomic number 33 and relative atomic mass 74.92. Arsenic occurs in many minerals, usually in conjunction with sulfur and metals, and also as a pure elemental crystal. It was first documented by Albertus Magnus in 1250.Arsenic is a metalloid...
O
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...
4)2•2H2O
Water
Water is a chemical substance with the chemical formula H2O. A water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on Earth with its solid state, ice, and gaseous state . Water also exists in a...
. Along with arsenate ions (AsO₄)3-, the infrared spectrum revealed H₂O . These water molecules present in the warikahnite sample were determined by thermo gravimetric analysis, and lost at 365°C. Both H₂O and (AsO₄)3- readily dissolved when hot hydrochloric acid (HCL) or nitric acid (HNO₃) were added to the specimen. After a microprobe analysis, the weight percent oxides were calculated as follows in the table directly below.
| Chem For. | Name | % |
|---|---|---|
| As₂O₅ | (arsenic pentoxide) | 44.33% |
| ZnO | (zinc oxide) | 47.85% |
| MnO | (manganese oxide) | 0.40% |
| FeO | (iron oxide) | 0.19% |
| H₂O | (water) | 6.32% |
| TOTAL | 99.09% |
Geologic occurrence
Warikahnite’s only known localities to date are the Tsumeb Mine in Namibia, South West Africa; and Plaka and Lavrion, Greece. The first discovery of this type specimen in the mine was found with white koritnigite, blue stranskiite, pale to emerald-green cuprian adamiteAdamite
Adamite is a zinc arsenate hydroxide mineral, Zn2AsO4OH. It is a mineral that typically occurs in the oxidized or weathered zone above zinc ore occurrences. Pure adamite is colorless, but usually it possess yellow color due to Fe compounds admixture. Tints of green also occur and are connected with...
, crystals of helmutwinklerite, and white corroded crystals of claudetite
Claudetite
Claudetite is an arsenic mineral chemical formula As2O3.It is named for the french chemist, F. Claudet. Claudetite is formed as an oxidation product of arsenic sulfides and is colorless or white. It can be associated with arsenolite as well as realgar, orpiment and sulfur....
, ludlockite, tsumcorite
Tsumcorite
Tsumcorite is a rare hydrated lead arsenate mineral that was discovered in 1971, and reported by Geier, Kautz and Muller. It was named after the TSUMeb CORporation mine at Tsumeb, in Namibia, in recognition of the Corporation’s support for mineralogical investigations of the orebody at its Mineral...
, and lavendulan
Lavendulan
Lavendulan is an uncommon copper arsenate mineral, known for its characteristic intense electric blue color. It belongs to the lavendulan group, which has four members:* Lavendulan NaCaCu54Cl.5H2O* Lemanskiite NaCaCu54Cl.5H2O...
; while the second acquisition was only linked to quartz
Quartz
Quartz is the second-most-abundant mineral in the Earth's continental crust, after feldspar. It is made up of a continuous framework of SiO4 silicon–oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall formula SiO2. There are many different varieties of quartz,...
.
Literature
- Keller, P., H. Hess, and P.J. Dunn (1979) Warikahnit, Zn3[(H2O)2|(AsO4)2], ein neues Mineral aus Tsumeb, S¨udwestafrika. Neues Jahrb. Mineral., Monatsh., 389–395.
- Riffel, H., P. Keller, and H. Hess (1980) Die Kristallstruktur von Warikahnit, Zn3[(H2O)2|(AsO4)2]. Tschermaks Mineral. Petrog. Mitt., 27, 187–199.