Moving mountains for you
Switch currency

Current Live Auctions

Current Live Fixed Price Sales

Decavanadate Minerals Unplugged

Content image: Decavanadate Minerals Unplugged

Whilst doing some tidying on the website I came across the mineral postite recently listed. I needed to check out the composition the relation to other minerals. It was not long before I was looking into the range of minerals containing the decavanadate ion, generically expressed V10O28.

Postite - Blue Cap Mine, Lyon Creek Canyon, San Juan County, Utah, USA FOV c3mm


The wonderfully symmetrical structure of the ion comprises two central VO6 octahedrons each with 4 tetragonally arranged VO5 groups.

3D Model of Decavanadate Ion - (Wikpedia)


The oxidation state for each vandium atom within a decavanadate polyanion is +5, or V(v) and the overall charge balance of the V10O28 ion is -6. 

However within the decavanadate chemistry the vanadium can hold a reduced charge and exist as +4, in a ratio of 1:9, or 2:8, or indeed the ion can be protonated, by 1,2 or 3 hydrogens (protons), the one proton version being currently only known as synthetic.

Decavanadate Polyanions
Formula Vanadium Oxidation/Protonation Charge Balance
{H3(V10O28)}3- 10  V5+ & 3H+ 3-
{H2(V10O28)}4- 10  V5+ & 2H+ 4-
{H(V10O28)}5- 10  V5+ & H+ 5-
(V10O28)6- 10  V5+ 6-
(V4+V5+9O28)7- V4+ & 9 V5+ 7-
(V4+2V5+8O28)8- 2 V4* & 8 V5+ 8-


This chemistry and the unique structural unit of the decavanadate ion gives rise to some interesting mineralogy where small groups of cations with water form repeating symmetrical structures through hydrogen bonds.

Most of these minerals are pretty new to mineral science by comparison, however synthetic compounds have been understood for a while.

The different mineral types are apparently found post-mining through the decomposition/oxidation of vanadium ore minerals (eg corvusite and montrosite), often leached out of near-surface vanadium oxide residue as efflorescences on mine walls. Generally these minerals are water soluble, with an yellow/orange colour (down to the decavanadate ion). Bluestreakite and nashite colour are exceptions being dark blue-green - due to the V4+ component?

Here below is a list of the minerals currently classified, it is interesting that that different data sources have different presentations of the chemistry within the list and also the membership of the Pascoite Group. 


Mineral Name Formula IMA Date Group Crystal System Decavanadate Polyanion

On e-Rocks Database?

Bluestreakite K4Mg2(V4+2V5+8O28)·14H2O 2014   Monoclinic (V4+2V5+8O28)8– No
Burroite Ca2(NH4)2(V10O28)·15H2O 2016   Triclinic (V10O28)6- No
Gunterite Na4(H2O)16{H2(V10O28)}·6H2O 2011   Monoclinic {H2(V10O28)}4- No
Huemulite Na4Mg(V10O28).24H2O 1965 Pascoite Triclinic (V10O28)6- Yes
Hughesite Na3Al(V10O28).22H2O 2009   Triclinic (V10O28)6- Yes
Hummerite K2Mg2(V10O28)·16H2O 1951 Pascote Triclinic (V10O28)6- Yes
Hydropascoite Ca3(V10O28)·24H2O 2016 Pascoite Triclinic (V10O28)6- No
Kokinosite Na2Ca2(V10O28)·24H2O 2013   Triclinic (V10O28)6- No
Lasalite Na2Mg2(V10O28)·20H2O 2007 Pascoite Monoclinic (V10O28)6- Yes
Magnesiopascoite Ca2Mg(V10O28)·16H2O 2007 Pascoite Monoclinic (V10O28)6- Yes
Nashite Na3Ca2(V4+V5+9O28)·24H2O 2013   Monoclinic (V4+V5+9O28)7– No
Pascoite Ca3(V10O28)·17H2O 1914 Pascoite Monoclinic (V10O28)6- Yes
Postite Mg(H2O)6Al2(OH)2(H2O)8(V10O28)·13H2O 2011   Orthorhombic (V10O28)6- Yes
Rakovanite Na3{H3(V10O28)}·15H2O 2010 Pascoite Monoclinic {H3(V10O28)}3- Yes
Rauvite Ca(UO2)2(V10O28)·16H2O 1922   Null (V10O28)6- Yes
Schindlerite {(NH4)4Na2(H2O)10}{V10O28} 2012   Triclinic (V10O28)6- No
Wernerbaurite {(NH4)2[Ca2(H2O)14](H2O)2}{V10O28} 2012   Triclinic (V10O28)6- No


You can see example photos below - click to expand.

Content tags: 
Album: Decavanadate Minerals Unplugged
Album: Decavanadate Minerals Unplugged
Album: Decavanadate Minerals Unplugged
Album: Decavanadate Minerals Unplugged
Album: Decavanadate Minerals Unplugged
Album: Decavanadate Minerals Unplugged
Album: Decavanadate Minerals Unplugged
Album: Decavanadate Minerals Unplugged
Album: Decavanadate Minerals Unplugged