Ferrokentbrooksite

Ferrokentbrooksite
	Ferrokentbrooksite, Amphibole Supergroup-166795
General
Category	Cyclosilicate
Formula; (repeating unit)	Na; 15Ca; 6(Fe,Mn); 3Zr; 3NbSi; 25O; 73(O,OH,H; 2O); 3(Cl,F,OH); 2 (original form)
Strunz classification	9.CO.10 (10 ed) ; 8/E.23-15 (8 ed)
Dana classification	64.1.2.2
Crystal system	Trigonal
Crystal class	Ditrigonal pyramidal (3m) ; H-M symbol: (3m)
Space group	R3m
Unit cell	a = 14.25, c = 30.03 [Å] (approximated); Z = 3
Identification
Color	Reddish brown to red
Crystal habit	pseudo-octahedra
Cleavage	No
Fracture	Uneven to conchoidal
Luster	Vitreous
Streak	White
Diaphaneity	Transparent
Refractive index	nω 1.62, nε=1.62 (approximated)
Common impurities	REE (mainly Ce and Y), K, Sr
References	[1][2]

Ferrokentbrooksite is a moderately rare mineral of the eudialyte group,[1] with formula Na
15Ca
6(Fe,Mn)
3Zr
3NbSi
25O
73(O,OH,H
2O)
3(Cl,F,OH)
2.[2] The original formula was extended form to show the presence of cyclic silicate groups and presence of silicon at the M4 site, according to the nomenclature of eudialyte group.[3] As suggested by its name, it is the (ferrous) iron analogue of kentbrooksite.[2] When compared to the latter, it is also chlorine-dominant instead of being fluorine-dominant.[1] The original (holotype) material is also relatively enriched in rare earth elements, including cerium and yttrium.[2]

Occurrence and association

Ferrokentbrooksite was discovered in Mont Saint-Hilaire, Quebec, Canada - a site wealth in rare alkaline minerals.[4] At the site ferrokentbrooksite coexists with aegirine, albite, ancylite-(Ce), calcite, catapleiite, fluorite, fluorapatite, gonnardite, microcline, natrolite, nepheline, rhodochrosite, and serandite.[2]

Notes on chemistry

Beside fluorine, ferrokentbrooksite has admixtures of rare earth elements (including cerium, yttrium, lanthanum, neodymium and some gadolinium and samarium), potassium, strontium, and contains minor admixtures of titanium, hafnium, and tantalum.[2]

Notes on structure

Iron in ferrokentbrooksite has coordination number 5.[2]

References

Mindat, Ferrokentbrooksite, http://www.mindat.org/min-7106.html
Johnsen, O., Grice, J.D., and Gault, R.A., 2003: Ferrokentbrooksite, a new member of the eudialyte group from Mont Saint-Hilaire, Quebec, Canada. The Canadian Mineralogist 41(1), 55-60
Johnsen, O., Ferraris, G., Gault, R.A., Grice, D.G., Kampf, A.R., and Pekov, I.V., 2003. The nomenclature of eudialyte-group minerals. The Canadian Mineralogist 41, 785-794
"Poudrette quarry (Demix quarry; Uni-Mix quarry; Desourdy quarry; Carrière Mont Saint-Hilaire), Mont Saint-Hilaire, La Vallée-du-Richelieu RCM, Montérégie, Québec, Canada - Mindat.org". Mindat.org. Retrieved 2016-03-11.

This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.

[Mindat-1] Mindat, Ferrokentbrooksite, http://www.mindat.org/min-7106.html

[CanMin-2] Johnsen, O., Grice, J.D., and Gault, R.A., 2003: Ferrokentbrooksite, a new member of the eudialyte group from Mont Saint-Hilaire, Quebec, Canada. The Canadian Mineralogist 41(1), 55-60

[3] Johnsen, O., Ferraris, G., Gault, R.A., Grice, D.G., Kampf, A.R., and Pekov, I.V., 2003. The nomenclature of eudialyte-group minerals. The Canadian Mineralogist 41, 785-794

[4] "Poudrette quarry (Demix quarry; Uni-Mix quarry; Desourdy quarry; Carrière Mont Saint-Hilaire), Mont Saint-Hilaire, La Vallée-du-Richelieu RCM, Montérégie, Québec, Canada - Mindat.org". Mindat.org. Retrieved 2016-03-11.