Kaňkite
| Kankite | |
|---|---|
 Kaňkite found in the Czech Republic | |
| General | |
| Category | Arsenate mineral |
| Formula (repeating unit) | Fe3+AsO4·3.5(H2O) |
| IMA symbol | Kňk[1] |
| Strunz classification | 8.CE.60 |
| Crystal system | Monoclinic Unknown space group |
| Unit cell | a = 18.803(15), b = 17.490(18) c = 7.633(5) [Å]; β = 92.72°; z = 16 |
| Identification | |
| Formula mass | 257.82 g/mol |
| Color | Yellowish–green |
| Crystal habit | Tabular spearlike crystals in spherulites and botryoidal encrustations |
| Fracture | Uneven |
| Mohs scale hardness | 2–3 |
| Luster | Dull to vitreous |
| Streak | Grayish yellow |
| Diaphaneity | Translucent |
| Specific gravity | 2.60 – 2.70 |
| Optical properties | Biaxial |
| Refractive index | nα = 1.664 nγ = 1.680 |
| References | [2][3][4][5] |
Kankite is a mineral with the chemical formula Fe3+AsO4·3.5(H2O). Kankite is named for the locality that yielded first specimens , Czech Republic.[2] Kankite forms in old (1200- to 1400-year-old) mine dumps.[3] It is yellowish-green on fresh exposure, with a paler greenish yellow on exposure to air.
Properties[]
Kankite is a monoclinic mineral, meaning it is a mineral system having 3 unequal axes of which one is at right angles with the other two. It has an uneven fracture and has a hardness of 2–3 (gypsum–calcite). It is translucent yellowish green in color with a grayish-yellow streak. Its luster is dull to vitreous. Kankite contains the elements arsenic, iron, hydrogen and oxygen.[4] It was approved by the IMA in 1976. Its habit is botryoidal, "grape-like" rounded forms (e.g. malachite). It forms encrustations, crust-like aggregates on matrix. The specific gravity of Kankite is 2.70.[3]
Occurrences[]
Kankite was first described in 1976 for an occurrence in the Kaňk, Kutná Hora, Bohemia, Czech Republic.[5] It is a rare secondary mineral in highly weathered mine dumps containing arsenopyrite (in the Czech Republic). It occurs in association with scorodite, , parascorodite, zykaite, arsenopyrite, , native arsenic, pyrite, proustite, gypsum, “limonite” and quartz.[2]
It has also been reported from near Meissen; from Brand-Erbisdorf, Saxony; from Menzenschwand, Black Forest in Germany. It occurs at King's Wood mine, Buckfastleigh, Devon, and from the South Terras mine, St. Stephen-in-Brannel, Cornwall in England. It has also been reported from the Suzukura mine north-northeast of Enzan, Yamanashi Prefecture, Japan.[2]
References[]
- ^ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
- ^ a b c d Handbook of Mineralogy
- ^ a b c Webmineral data
- ^ a b [1], Frost, Ray L. and Cejka, Jin and Keeffe, Eloise C. and Sejkora, Jiri (2009)Raman Spectroscopic study of the mixed anion sulphate-arsenate mineral pamnauiteJournal of Raman Spectroscopy, 40(11) pp. 1547–1550.
- ^ a b Mindat.org
- Iron(III) minerals
- Arsenate minerals
- Monoclinic minerals