page_title: Silicate mineral
section_title: Phyllosilicates
hierarchical_section_title: Silicate mineral / Phyllosilicates
context_page_description: Silicate minerals are rock-forming minerals made up of silicate groups. They are the largest and most important class of minerals and make up approximately 90 percent of the Earth's crust.
  In mineralogy, silica SiO₂ is usually considered a silicate mineral. Silica is found in nature as the mineral quartz, and its polymorphs.
  On Earth, a wide variety of silicate minerals occur in an even wider range of combinations as a result of the processes that have been forming and re-working the crust for billions of years. These processes include partial melting, crystallization, fractionation, metamorphism, weathering, and diagenesis.
  Living organisms also contribute to this geologic cycle. For example, a type of plankton known as diatoms construct their exoskeletons from silica extracted from seawater. The frustules of dead diatoms are a major constituent of deep ocean sediment, and of diatomaceous earth.
context_section_description: Phyllosilicates (from Greek φύλλον phyllon, 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.
  Examples include:
  Serpentine subgroup
  Antigorite – Mg₃Si₂O₅(OH)₄
  Chrysotile – Mg₃Si₂O₅(OH)₄
  Lizardite – Mg₃Si₂O₅(OH)₄
  Clay minerals group
  Halloysite – Al₂Si₂O₅(OH)₄
  Kaolinite – Al₂(OH)₄Si₂O₅
  Illite – (K,H₃O)(Al,Mg,Fe)₂(Si,Al)₄O₁₀[(OH)₂,(H₂O)]
  Montmorillonite – (Na,Ca)0.33(Al,Mg)₂Si₄O₁₀(OH)₂·nH₂O
  Vermiculite – (MgFe,Al)₃(Al,Si)₄O₁₀(OH)₂·4H₂O
  Talc – Mg₃Si₄O₁₀(OH)₂
  Sepiolite – Mg₄Si₆O₁₅(OH)₂·6H₂O
  Palygorskite (or attapulgite) – (Mg,Al)₂Si₄O₁₀(OH)·4(H₂O)
  Pyrophyllite – Al₂Si₄O₁₀(OH)₂
  Mica group
  Biotite – K(Mg,Fe)₃(AlSi₃)O₁₀(OH)₂
  Fuchsite – K(Al,Cr)₂(AlSi₃O₁₀)(OH)₂
  Muscovite – KAl₂(AlSi₃)O₁₀(OH)₂
  Phlogopite – KMg₃(AlSi₃)O₁₀(OH)₂
  Lepidolite – K(Li,Al)2–3(AlSi₃)O₁₀(OH)₂
  Margarite – CaAl₂(Al₂Si₂)O₁₀(OH)₂
  Glauconite – (K,Na)(Al,Mg,Fe)₂(Si,Al)₄O₁₀(OH)₂
  Chlorite group
  Chlorite – (Mg,Fe)₃(Si,Al)₄O₁₀(OH)₂·(Mg,Fe)₃(OH)₆
caption: Kaolinite
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