Ferronigerite-2N1S is an
iron,
tin,
alumino
Aluminium (aluminum in American and Canadian English) is a chemical element with the symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately one third that of steel. It h ...
-
hydroxide mineral that naturally occurs around
sillimanite-
quartz veins. Ferronigerite-2N1S belongs to the
nigerite group, högbomite supergroup. The other constituents of the nigerite group are ferronigerite-6N6S, magnesionigerite-2N1S, magnesionigerite-6N6S, zinconigerite-2N1S and zinconigerite-6N6S.
Nigerite group on Mindat.org
/ref> The ''2N1S'' ending stands for the nolanite and spinel
Spinel () is the magnesium/aluminium member of the larger spinel group of minerals. It has the formula in the cubic crystal system. Its name comes from the Latin word , which means ''spine'' in reference to its pointed crystals.
Properties
S ...
structural layers.[
Ferronigerite-2N1S was first discovered in the Kabba province of central Nigeria in 1944; it was originally named Nigerite. Its name was later changed to nigerite-6H then to nigerite-6T and in 2003 ferronigertie-2N1S was approved by the ]International Mineralogical Association
Founded in 1958, the International Mineralogical Association (IMA) is an international group of 40 national societies. The goal is to promote the science of mineralogy and to standardize the nomenclature of the 5000 plus known mineral species. Th ...
.
Chemical composition
The general chemical formula of ferronigertie-2N1S is [Ferronigerite-2N1S data on Webmineral]
/ref> or .
/ref>
Its percent composition is 50.91% Al2O3, 25.33% SnO2, 11.90% Fe2O3, 4.51% ZnO, 2.65% FeO, 1.57% H2O, 1.28% MgO, and less than 1% of PbO, SiO2, TiO2 and MnO. Due to its chemical composition, it is not susceptible to decomposition or solubility in acids.
Ferronigerite-2N1S has also been found in some cases to have a lithium substitution for tin and titanium; this aids in charge balancing.
Properties
Ferronigerite-2N1S possesses no prominent cleavage but does possess a weak basal cleavage. It has a light grey to white streak, and often is shiny dark brown in color. Although the color can also be yellow to light brown. The variance of color is due to the individual composition to the mineral and where it is found geologically. It has a relative hardness of 8-9 on Mohs relative hardness scale.
Structure
Ferronigerite-2N1S crystallizes in the trigonal 2/m crystal class and a space group of Pm1. It exhibits two types of close pack structures: cubic close packed and hexagonal close packed. This results in ferronigerite-2N1S looking like simple hexagonal plates.
Geologic occurrence
Ferronigerite-2N1S has been found to be associated with Precambrian
The Precambrian (or Pre-Cambrian, sometimes abbreviated pꞒ, or Cryptozoic) is the earliest part of Earth's history, set before the current Phanerozoic Eon. The Precambrian is so named because it preceded the Cambrian, the first period of the ...
schists, gneisses, and granites, in the Tsomtsaub tin mine in the Egbe District, Kabba Provence in central Nigeria.
It is generally associated with microcline-quartz-pegmatite
A pegmatite is an igneous rock showing a very coarse texture, with large interlocking crystals usually greater in size than and sometimes greater than . Most pegmatites are composed of quartz, feldspar, and mica, having a similar silicic com ...
s in small amounts and limited in association only to that of old granite, shists, and gneisses. It is also associated with microcline-quartz-mica
Micas ( ) are a group of silicate minerals whose outstanding physical characteristic is that individual mica crystals can easily be split into extremely thin elastic plates. This characteristic is described as perfect basal cleavage. Mica is ...
-pegmities, which make up to bulk of economically advantageous deposits of cassiterite
Cassiterite is a tin oxide mineral, SnO2. It is generally opaque, but it is translucent in thin crystals. Its luster and multiple crystal faces produce a desirable gem. Cassiterite was the chief tin ore throughout ancient history and remains t ...
where Ferronigerite-2N1S is found in association. The most common geologic structure where it is present is in sillimanite-quartz veins which are paired closely with gahnite
Gahnite, ZnAl2O4, is a rare mineral belonging to the spinel group. It forms octahedral crystals which may be green, blue, yellow, brown or grey. It often forms as an alteration product of sphalerite in altered massive sulphide deposits such as at ...
. While microcline-quartz-mica-pegmities and Precambrian schists, gneisses and granites are common in Africa, sillimanite-quartz veins are more common in other parts of the world.
References
{{reflist
Further reading
# Arakcheeva, A.V., Pushcarovski, D.Y., Rastsvetaeva, R.K.,Kashaev, A.A., & Nadexhina, T.N. (1995). Crystal structure of nigerite-5H. Crystallography Reports, 40, 587-592.
# Armbruster, T. (2002) Revised nomenclature of Hogbomite, nigerite, and taaffeite minerals. European Journal of Mineralogy, 14(2), 389-395.
# Armbruster, T., & Feenstra, A. (2004). Lithium in nigerite-group minerals. European journal of mineralogy, 16(2), 247-254. Chicago
# Bannister, F.A., Hey, M.H., Stadler, H.P. (1947) Nigerite, a new tin mineral. Mineral. Mag., 28, 128–136.
# Grey, I.E. & Gatehouse, B.M. (1979) The crystal structure of nigerite-24R. Am. Mineral., 64, 1255–1264.
# Grice and Farraris (2003). New minerals approved in 2002 and nomenclature modifications approved 1998–2002 by the Commission on New Minerals and Mineral Names, International Mineralogical Association. American Mineralogist, 88, 1620-1624.
# Jacobson, R., & Webb, J. S. (1947). The occurrence of nigerite, a new tin mineral in quartz- sillimanite-rocks from Nigeria. Mineral. Mag, 28, 118-128.
# Kloosterman, J. B. (1974). Nigerite in the tin-tantalum pegmatites of Amapa, Brazil. Mineral Mag, 39, 837-846. Chicago
# McKie, D. (1963) The högbomite polytypes. Mineral. Mag, 33, 563–580.
# Nickel, E.H. (1993) Standardization of polytype suffixes. Can. Mineral., 31, 767–768.
# Novák, M., Vieira, R., Lima, A., Skoda, R., Martins, T., & dos Anjos Ribeiro, M. (2009). Ferronigerite with dominant substitution TiSn1 in muscovite+ chlorite aggregate from massive quartz nodule associated with a petalite-rich aplite-pegmatite of the Barroso-Alvao pegmatite field, Northern Portugal. Neues Jahrbuch für Mineralogie- Abhandlungen, 186(1), 67-78.
# Peacor, D.R. (1967) New data on nigerite. Am. Mineral., 52, 864–866.
# Rouse, R. C., & Peacor, D. R. (1968). The relationship between senaite, magnetoplumbite and davidite. Am. Mineral, 53, 869-879.
# Schumacher, J. C., Schäfer, K., & Seifert, F. (1987). Lamellar nigerite in Zn-rich spinel from the Falun deposit, Sweden. Contributions to Mineralogy and Petrology 95 (2), 182-190.
# Van Tassel, R. (1965). Nigerite from Lixa, near Felgueiras, Douro Litoral province, Portugal. Mineral Mag, 34, 482-486.
Oxide minerals
Hydroxide minerals
Tin minerals
Iron(II,III) minerals
Aluminium minerals
Geology of Nigeria
Trigonal minerals
Minerals in space group 164