Phyllosilicates

Phyllosilicates

Phyllosilicates (from Greek φύλλονphýllon 'leaf'), or sheet silicates, form parallel sheets of silicate tetrahedra with Si₂O₅ or a 2:5 ratio. The Nickel–Strunz classification is 09.E. All phyllosilicate minerals are hydrated, with either water or hydroxyl groups attached. Many phyllosilicates are clay-forming and may be further classified as 1:1 clay minerals (one tetrahedral sheet and one octahedral sheet) and 2:1 clay minerals (one octahedral sheet between two tetrahedral sheets). Below are some major phyllosilicate mineral species and their chemical formulas, with group and series names in italics: