An arsenate arsenite is a chemical compound or salt that contains arsenate and arsenite anions (AsO33- and AsO43-). These are mixed anion compounds or mixed valence compounds. Some have third anions. Most known substances are minerals, but a few artificial arsenate arsenite compounds have been made. Many of the minerals are in the Hematolite Group.
An arsenate arsenite compound may also be called an arsenite arsenate.
Some members of this group of materials like mcgovernite has an extremely high unit cell dimension of 204 Å. [1]
Mixed valence pnictide compounds related to the arsenate arsenites include the nitrite nitrates, and phosphate phosphites.
| name | formula | ratio AsO4:AsO3 | system | space group | unit cell Å | volume | density | properties | references |
|---|---|---|---|---|---|---|---|---|---|
| Arsenic dioxide | AsO2 | 1:1 | orthorhomnic | Pnma | a=8.597 b=5.235 c=7.269 Z=8 | 327.1 | 4.382 | [2] | |
| Arsenic(III) Arsenic(V) Oxide Hydroxide | As3O5(OH) | 1:2 | monoclinic | P21/c | a = 12.504 b = 4.593 c = 10.976 β = 118.08° Z = 4 | 556.2 | 3.84 | [3] | |
| H6As3+7As5+7O31 | 1:1 | hexagonal | P63 | a = 12.0525 c = 4.7344 Z = 2 | 595.6 | [4] | |||
| Segerstromite | Ca3(As5+O4)2[As3+(OH)3]2 | 2:1 | cubic | I213 | a = 10.7627 Z = 4 | 1246.71 | 3.46 | colourless; refract index: n = 1.731 | [5] |
| Synadelphite | Mn2+9(As5+O4)2(As3+O3)(OH)9 · 2H2O | 2:1 | Orthorhombic | Pnma | a = 10.75 b = 18.86c = 9.88 Z=4 | 2005 | 3.58 | red; Biaxial (+); refract index: nα = 1.750 - 1.870 nβ = 1.751 - 1.880 nγ = 1.761 - 1.930 | [6] |
| Hematolite | (Mn,Mg,Al,Fe3+)15(As5+O4)2(As3+O3)(OH)23 | 2:1 | trigonal | R3 | a = 8.275 Å, c = 36.60 Å Z=3 | 2,170.4 | 3.49 | deep red; Uniaxial (-) refractive index nω = 1.733 nε = 1.714; Birefringence: 0.019 | [7] [8] |
| Turtmannite | (Mn,Mg)22.5Mg3-3x((V5+,As5+)O4)3(As3+O3)x(SiO4)3O5-5x(OH)20+x | trigonal | a = 8.259 c = 204.3 Z=12 | 12,068 | 3.8 | light yellow; Uniaxial (-); refractive index: nε = 1.787 | [9] | ||
| Carlfrancisite | Mn2+3(Mn2+,Mg,Fe3+,Al)42[As3+O3]2(As5+O4)4[(Si,As5+)O4]6[(As5+,Si)O4]2(OH)42 | trigonal | R3c | a = 8.2238 c = 205.113 Z=6 | 12,013.5 | 3.620 | yellow-orange; Uniaxial (+) refractive index: nω = 1.756(2) nε = 1.758 Birefringence: δ = 0.002 | [10] | |
| K2Cu3(As2O6)2 | 1:1 | monoclinic | C2m | a=10.359 b=5.388 c=11.234 β=110.48° | [As(V)As(III)O6]4− | [11] | |||
| Dixenite | CuMn2+14Fe2+(SiO4)2(As5+O4)(As3+O3)5(OH)6 | 1:5 | trigonal | R3 | a = 8.233 c = 37.499 Z=3 | 2201 | 4.35 | deep red-brown; Uniaxial (+) refractive index nω = 1.970 nε = 1.730 | [12] |
| Arakiite | (Zn,Mn2+)(Mn2+,Mg)12(Fe3+,Al)2(As5+O4)2(As3+O3)(OH)23 | 2:1 | monoclinic | Cc | a = 14.248 b = 8.228 c = 24.23 β = 93.62° Z=4 | 2843 | 3.41 | orange-red brown; Biaxial (-); refract index: nα = 1.723 nβ = 1.744 nγ = 1.750 Birefringence: 0.027 | [13] |
| Kraisslite | Zn3(Mn,Mg)25(Fe3+,Al)(As3+O3)2[(Si,As5+)O4]10(OH)16 | 5:1 | Orthorhombic | C2221 | a = 8.1821 b = 14.1946 c = 43.9103 Z=4 | 5099.8 | 3.876 | pale red; Uniaxial (+) Refractive index: nε = 1.805 | [14] |
| Mcgovernite | Mn19Zn3(AsO4)3(AsO3)(SiO4)3(OH)21 | 3:1 | trigonal | R3m or R3m | a = 8.22 c = 203.1 Z=6 | 11,887.52 | 3.719 | brown; Uniaxial (+) Refractive index: nω = 1.757 nε = 1.760 Birefringence: δ = 0.003 | [15] |
| Halilsarpite | [Mg(H2O)6][CaAs3+2(Fe3+2.67Mo6+0.33)(AsO4)2O7] | orthorhomnic | Imma | a = 26.489 b = 7.4205 c = 10.4378 | 2051.7 | lemon yellow; Biaxial (-) refractive index: nα = 1.646 nβ = 1.765(5) nγ = 1.815(5) 2V: 62° Max Birefringence: δ = 0.169 | [16] | ||
| Wiklundite | Pb2(Mn2+,Zn)3(Fe3+,Mn2+)2(Mn2+,Mg)19(As3+O3)2[(Si,As5+)O4]6(OH)18Cl6 | hexagonal | ? R3c | a = 8.257 c = 126.59 Z = 6 | 7474 | 4.072 | dark reddish brown | [17] | |
| Bi8O6(AsO3)2(AsO4)2 | monoclinic | I2/a | a=24.372 b=5.528 c=29.90 β=99.058 Z=8 | 3978 | 7.652 | colourless | [18] | ||
| Th(AsIII4AsV4O18) | 1:1 | monoclinic | C2/c | a=18.2148 b 5.19792 c=17.3588 β=99.1298 Z=4 | 1622.70 | 4.582 | colourless | [19] |
The arsenate is an ion with the chemical formula AsO3−4. Bonding in arsenate consists of a central arsenic atom, with oxidation state +5, double bonded to one oxygen atom and single bonded to a further three oxygen atoms. The four oxygen atoms orient around the arsenic atom in a tetrahedral geometry. Resonance disperses the ion's −3 charge across all four oxygen atoms.
In chemistry, an arsenite is a chemical compound containing an arsenic oxyanion where arsenic has oxidation state +3. Note that in fields that commonly deal with groundwater chemistry, arsenite is used generically to identify soluble AsIII anions. IUPAC have recommended that arsenite compounds are to be named as arsenate(III), for example ortho-arsenite is called trioxidoarsenate(III). Ortho-arsenite contrasts to the corresponding anions of the lighter members of group 15, phosphite which has the structure HPO2−3 and nitrite, NO−2 which is bent.
Layered double hydroxides (LDH) are a class of ionic solids characterized by a layered structure with the generic layer sequence [AcB Z AcB]n, where c represents layers of metal cations, A and B are layers of hydroxide anions, and Z are layers of other anions and neutral molecules. Lateral offsets between the layers may result in longer repeating periods.
Barbertonite is a magnesium chromium carbonate mineral with formula of Mg6Cr2(OH)16CO3·4H2O. It is polymorphous with the mineral stichtite and, along with stichtite, is an alteration product of chromite in serpentinite. Barbertonite has a close association with stichtite, chromite, and antigorite (Taylor, 1973). Mills et al. (2011) presented evidence that barbertonite is a polytype of stichtite and should be discredited as a mineral species.
Arsenoclasite (originally arsenoklasite) is a red or dark orange brown mineral with formula Mn5(AsO4)2(OH)4. The name comes from the Greek words αρσενικόν (for arsenic) and κλάσις (for cleavage), as arsenoclasite contains arsenic and has perfect cleavage. The mineral was discovered in 1931 in Långban, Sweden.
Hidalgoite, PbAl3(AsO4)(SO4)(OH)4, is a rare member of the beudantite group and is usually classified as part of the alunite family. It was named after the place where it was first discovered, the Zimapán mining district, Hidalgo, Mexico. At Hidalgo where it was initially discovered, it was found as dense white masses in alternating dikes of quartz latite and quartz monzonite alongside other secondary minerals such as sphalerite, arsenopyrite, cerussite and trace amounts of angelsite and alamosite, it was then rediscovered at other locations such as Australia where it occurs on oxidized shear zones above greywacke shales especially on the anticline prospects of the area, and on fine grained quartz-spessartine rocks in Broken Hill, Australia. Hidalgoite specimens are usually associated with copper minerals, clay minerals, iron oxides and polymetallic sulfides in occurrence.
Arakiite (IMA symbol: Ark) is a rare mineral with the formula (Zn,Mn2+)(Mn2+,Mg)12(Fe3+,Al)2(As3+O3)(As5+O4)2(OH)23. It is both arsenate and arsenite mineral, a combination that is rare in the world of minerals. Arakiite is stoichiometrically similar to hematolite. It is one of many rare minerals coming from the famous Långban manganese skarn deposit in Sweden. Other minerals bearing both arsenite and zinc include kraisslite and mcgovernite.
Wiklundite is a rare and complex arsenite-silicate mineral with the chemical formula Pb2(Mn2+,Zn)3(Fe3+,Mn2+)2(Mn2+,Mg)19(As3+O3)2(Si,As5+O4)6(OH)18Cl6. The mineral characterizes in a large c unit cell parameter. It was found in Långban, Sweden - a home for many rare and exotic minerals.
Vanarsite, NaCa12(As3+V4+3.5V5+8.5As5+6O51)2・78H2O, is a mineral that forms as very dark blue blades that are flattened on {100} and elongated on [010]. The crystals form in sub-parallel intergrowths in aggregates up to 5 mm long and are part of the cubic crystal system. The mineral is found in the Packrat mine in Colorado, USA in association with three mineral of similar composition, packratite, Ca11(As3+V4+2V5+10As5+6O51)2・83H2O, morrisonite, Ca6(As3+V4+2V5+10As5+6O51)2・78H2O, and gatewayite, Ca11(As3+V4+3V5+9As5+6O51)・31H2O. Vanarsite has been determined to be part of the vanadate, arsenite, and arsenate groups. Analytical methods were used to determine its chemical composition, physical properties, and structure.
The carbonate chlorides are double salts containing both carbonate and chloride anions. Quite a few minerals are known. Several artificial compounds have been made. Some complexes have both carbonate and chloride ligands. They are part of the family of halocarbonates. In turn these halocarbonates are a part of mixed anion materials.
The borate carbonates are mixed anion compounds containing both borate and carbonate ions. Compared to mixed anion compounds containing halides, these are quite rare. They are hard to make, requiring higher temperatures, which are likely to decompose carbonate to carbon dioxide. The reason for the difficulty of formation is that when entering a crystal lattice, the anions have to be correctly located, and correctly oriented. They are also known as carbonatoborates or borocarbonates. Although these compounds have been termed carboborate, that word also refers to the C=B=C5− anion, or CB11H12− anion. This last anion should be called 1-carba-closo-dodecaborate or monocarba-closo-dodecaborate.
The sulfate chlorides are double salts containing both sulfate (SO42–) and chloride (Cl–) anions. They are distinct from the chlorosulfates, which have a chlorine atom attached to the sulfur as the ClSO3− anion.
The sulfate carbonates are a compound carbonates, or mixed anion compounds that contain sulfate and carbonate ions. Sulfate carbonate minerals are in the 7.DG and 5.BF Nickel-Strunz groupings.
The sulfate fluorides are double salts that contain both sulfate and fluoride anions. They are in the class of mixed anion compounds. Some of these minerals are deposited in fumaroles.
Fumarole minerals are minerals which are deposited by fumarole exhalations. They form when gases and compounds desublimate or precipitate out of condensates, forming mineral deposits. They are mostly associated with volcanoes following deposition from volcanic gas during an eruption or discharge from a volcanic vent or fumarole, but have been encountered on burning coal deposits as well. They can be black or multicoloured and are often unstable upon exposure to the atmosphere.
A tellurite tellurate is chemical compound or salt that contains tellurite and tellurate anions [TeO3]2- [TeO4 ]2-. These are mixed anion compounds, meaning the compounds are cations that contain one or more anions. Some have third anions. Environmentally, tellurite [TeO3]2- is the more abundant anion due to tellurate's [TeO4 ]2- low solubility limiting its concentration in biospheric waters. Another way to refer to the anions is tellurium's oxyanions, which happen to be relatively stable.
The phosphate sulfates are mixed anion compounds containing both phosphate and sulfate ions. Related compounds include the arsenate sulfates, phosphate selenates, and arsenate selenates.
The arsenite bromides are mixed anion compounds containing both arsenite and bromide ions. Similar compounds include arsenate bromides, arsenite chlorides, antimonite bromides, antimonite chlorides, and ...
Tacharanite is a calcium aluminium silicate hydrate (C-A-S-H) mineral of general chemical formula Ca12Al2Si18O33(OH)36 with some resemblance to the calcium silicate hydrate (C-S-H) mineral tobermorite. It is often found in mineral assemblage with zeolites and other hydrated calcium silicates.
Selenite sulfates are mixed anion compounds containing both selenite (SeO3), and sulfate (SO4) anions.