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With two shared oxides bound to each silicon, cyclic or polymeric structures can result. The cyclic metasilicate ring Si 6 O 12− 18 is a hexamer of SiO 3 2-. Polymeric silicate anions of can exist also as long chains. In single-chain silicates, which are a type of inosilicate, tetrahedra link to form a chain by sharing two oxygen atoms each.
Kentbrooksite is a moderately rare mineral of the eudialyte group, [2] with chemical formula (Na,REE) 15 (Ca,REE) 6 Mn 3 Zr 3 NbSi[(Si 9 O 27) 2 (Si 3 O 9) 2 O 2]F 2 ·2H 2 O. [3] This extended formula shows the presence of cyclic silicate groups and dominance of Si at the M4 site, according to the nomenclature of the eudialyte group. [4]
Carbokentbrooksite is a very rare mineral of the eudialyte group, [2] with formula (Na, ) 12 (Na,Ce) 3 Ca 6 Mn 3 Zr 3 NbSiO(Si 9 O 27) 2 (Si 3 O 9) 2 (OH) 3 (CO 3). H 2 O. [3] The original formula was extended to show the presence of cyclic silicate groups and silicon at the M4 site, according to the nomenclature of eudialyte group. [4]
A silicate mineral is generally an inorganic compound consisting of subunits with the formula [SiO 2+n] 2n−. Although depicted as such, the description of silicates as anions is a simplification. Balancing the charges of the silicate anions are metal cations, M x+. Typical cations are Mg 2+, Fe 2+, and Na +. The Si-O-M linkage between the ...
Zirsilite-(Ce) is a very rare mineral of the eudialyte group, with formula (Na, ) 12 (Ce,Na) 3 Ca 6 Mn 3 Zr 3 NbSi(Si 9 O 27) 2 (Si 3 O 9) 2 O(OH) 3 (CO 3)·H 2 O. [2] [3] The original formula was extended to show the presence of cyclic silicate groups and the presence of silicon at the M4 site, according to the nomenclature of the eudialyte group. [4]
Abenakiite-(Ce) is a mineral of sodium, cerium, neodymium, lanthanum, praseodymium, thorium, samarium, oxygen, sulfur, carbon, phosphorus, and silicon with a chemical formula Na 26 Ce 6 (SiO 3) 6 (PO 4) 6 (CO 3) 6 (S 4+ O 2)O. The silicate groups may be given as the cyclic Si 6 O 18 grouping.
Feklichevite is a rare mineral of the eudialyte group with the formula Na 11 Ca 9 (Fe 3+,Fe 2+) 2 Zr 3 NbSi(Si 3 O 9) 2 (Si 9 O 27) 2. [3] [2] The original formula was extended to show the presence of cyclic silicate groups and presence of silicon at the M4 site, according to the nomenclature of eudialyte group. [4]
Khomyakovite is an exceedingly rare mineral of the eudialyte group, with formula Na 12 Sr 3 Ca 6 Fe 3 Zr 3 W(Si 25 O 73)(O,OH,H 2 O) 3 (OH,Cl) 2. [2] [3] The original formula was extended to show the presence of both the cyclic silicate groups and M4-site silicon, according to the nomenclature of the eudialyte group. [4]