| Voronkovite | |
| Category: | Silicate mineral, Cyclosilicate |
| Formula: | (original form) |
| Imasymbol: | Vrk[1] |
| Strunz: | 9.CO.10 |
| System: | Trigonal |
| Class: | Pyramidal (3) H-M symbol: (3) |
| Symmetry: | R3 |
| Unit Cell: | a = 14.21, c = 30.27 [Å]; Z = 3 |
| Color: | Light brown |
| Habit: | Rounded crystals |
| Fracture: | Conchoidal |
| Tenacity: | Brittle |
| Mohs: | 5 |
| Luster: | Vitreous |
| Streak: | White |
| Diaphaneity: | Transparent |
| Density: | 2.95 g/cm3 (calculated) |
| Opticalprop: | Uniaxial (+) |
| Pleochroism: | Lemon yellow (X), brownish pink (Y) |
Voronkovite is a very rare mineral[2] of the eudialyte group with the chemical formula .[3] The formula is based on the simplified original one; it does not show the presence of cyclic silicate groups, but two M3- and M4-site silicon atoms are shown separately (basing on the nomenclature of the eudialyte group[4]). Voronkovite has lowered symmetry (space group R3, instead of more specific for the group R3m one), similarly to some other eudialyte-group members: aqualite, labyrinthite, oneillite and raslakite. The specific feature of voronkovite is, among others, strong enrichment in sodium.
Voronkovite comes from an ultra-alkaline pegmatite of Mt. Alluaiv, Lovozero Massif, Kola Peninsula, Russia. It occurs with aegirine, lomonosovite, manganoneptunite, microcline, nepheline, shkatulkalite, sodalite, terskite, sphalerite and vuonnemite.
Voronkovite has additional impurities, not given in the formula. They include strontium, fluorine, potassium, lanthanum, neodymium (at the Mn site), niobium, and minor hafnium and aluminium.