Ferrokentbrooksite

Ferrokentbrooksite
	Ferrokentbrooksite, Amphibole Supergroup-166795
General
Category	Cyclosilicate
Formula; (repeating unit)	Na15Ca6(Fe,Mn)3Zr3NbSi25O73(O,OH,H2O)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 Na₁₅Ca₆(Fe,Mn)₃Zr₃NbSi(Si₃O₉)₂(Si₉O₂₇)₂O(O,OH,H₂O)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]

gollark: Ah, yes. That would make the controller, which is programmed entirely in TIS-3D assembly with ComputerCraft connections for reading some data not available with comparators, more complex, though.

gollark: If you're only filling it when it's below 50% then half of it will just be empty constantly.

gollark: And that would basically involve wasting half the buffer.

gollark: I mean, currently, it doesn't make a huge difference.

gollark: I have a buffer. The reactor is set to go on when it's below full.

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.

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[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.