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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]
Johnsenite-(Ce) is a very rare mineral of the eudialyte group, [2] with the chemical formula Na 12 (Ce,La,Sr,Ca,[ ]) 3 Ca 6 Mn 3 Zr 3 WSi(Si 9 O 27) 2 (Si 3 O 9) 2 (CO 3)O(OH,Cl) 2. [3] The original formula was extended to show the presence of both the cyclic silicate groups and silicon at the M4 site, according to the nomenclature of the eudialyte group. [4]
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.
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]
Given sufficient time, rainwater can dissolve even a highly resistant silicate-based mineral such as quartz. [13] Water breaks the bonds between atoms in the crystal: [14] The overall reaction for the dissolution of quartz results in silicic acid. SiO 2 + 2H 2 O → H 4 SiO 4. Another example of a silicate-based mineral is enstatite (MgSiO 3).
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 ...
Unlike the acid, the salts can be stable. Indeed, pyrosilicates occur widely in nature as a class of silicate minerals, specifically the sorosilicates - though some sorosilicate minerals, such as gehlenite, replace one of the silicon atoms with tetracoordinated aluminium or boron, giving the isostructural anions AlSiO 7− 7 and BSiO 7− 7.
Silicate minerals consist of more than 90% of the minerals in the Earth's crust. [5] There are six silica mineral groups, based on bonding arrangement, and silica tetrahedron. [ 5 ] The silica groups include: nesosilicates, sorosilicates, cyclosilicates, inosilicates, phyllosilicates, and tectosilicates. [ 5 ]