The Tectosilicate Subclass
(The Framework Silicates)
A subclass of the Silicates

The Tectosilicate Subclass is often called the "Framework Silicates" because its structure is composed of interconnected tetrahedrons going outward in all directions, forming an intricate framework analogous to the framework of large building. In this subclass all of the oxygens are shared with other tetrahedrons giving a silicon to oxygen ratio of 1:2.

In the pure state of only silicon and oxygen the mineral is quartz (SiO2). But the tectosilicates are not that simple. It turns out that the aluminum ion can easily substitute for the silicon ion in the tetrahedrons. In other subclasses this occurs to a limited extent but in the tectosilicates it is a major basis of the varying structures. While the tetrahedron is nearly the same with an aluminum at its center, the charge is now a negative five (-5) instead of the normal negative four (-4). Since the charge in a crystal must be balanced, additional cations are needed in the structure and this is the main reason for the great variations within this subclass.

Here are some members of the tectosilicates:
  • Coombsite (Potassium Manganese Iron Magnesium Aluminum Silicate Hydroxide)
  • The Feldspar Group
  • The Feldspathoid Group:
    • Cancrinite (Sodium Calcium Aluminum Silicate Carbonate)
    • Danalite (Iron Beryllium Silicate Sulfide)
    • Davyne (Sodium Potassium Calcium Aluminum Silicate Sulfate Chloride)
    • Helvite (Manganese Beryllium Silicate Sulfide)
    • Hydroxycancrinite (Hydrated Sodium Aluminum Silicate Hydroxide)
    • Leucite (Potassium Aluminum Silicate)
    • Nepheline (Sodium Potassium Aluminum Silicate)
    • The Sodalite Group:
      • Hauyne (Sodium Calcium Aluminum Silicate Sulfate)
      • Lazurite (Sodium Calcium Aluminum Silicate Sulfate Sulfide Chloride)
      • Nosean (Sodium Aluminum Silicate Sulfate)
      • Sodalite (Sodium Aluminum Silicate Chloride)
      • Tugtupite (Sodium Aluminum Beryllium Silicate Chloride)
    • Vishnevite (Hydrated Sodium Calcium Potassium Aluminum Silicate Sulfate Carbonate Chloride)
  • Leifite (Hydrated Sodium Beryllium Aluminum Silicate Hydroxide Fluoride)
  • Marialite (Sodium Aluminum Silicate Chloride)
  • Meionite (Calcium Aluminum Silicate Carbonate Sulfate)
  • Pitaglianoite (Hydrated Potassium Sodium Aluminum Silicate Sulfate)
  • The Quartz Group: (All Silicon Dioxide)
  • Sarcolite (Sodium Calcium Aluminum Silicate Fluoride)
  • Scapolite (Calcium Sodium Aluminum Silicate Chloride Carbonate Sulfate)
  • Silhydrite (Hydrated Silicate Dioxide)
  • Ussingite (Sodium Aluminum Silicate Hydroxide)
  • The Zeolite Group:
    • The Analcime Family:
      • Analcime (Hydrated Sodium Aluminum Silicate)
      • Pollucite (Hydrated Cesium Sodium Aluminum Silicate)
      • Wairakite (Hydrated Calcium Sodium Aluminum Silicate)
    • Bellbergite (Hydrated Potassium Barium Strontium Sodium Aluminum Silicate)
    • Bikitaite (Hydrated Lithium Aluminum Silicate)
    • Boggsite (Hydrated calcium Sodium Aluminum Silicate)
    • Brewsterite (Hydrated Strontium Barium Sodium Calcium Aluminum Silicate)
    • The Chabazite Family:
      • Chabazite (Hydrated Calcium Aluminum Silicate)
      • Willhendersonite (Hydrated Potassium Calcium Aluminum Silicate)
    • Cowlesite (Hydrated Calcium Aluminum Silicate)
    • Dachiardite (Hydrated calcium Sodium Potassium Aluminum Silicate)
    • Edingtonite (Hydrated Barium Calcium Aluminum Silicate)
    • Epistilbite (Hydrated Calcium Aluminum Silicate)
    • Erionite (Hydrated Sodium Potassium Calcium Aluminum Silicate)
    • Faujasite (Hydrated Sodium Calcium Magnesium Aluminum Silicate)
    • Ferrierite (Hydrated Sodium Potassium Magnesium Calcium Aluminum Silicate)
    • The Gismondine Family:
      • Amicite (Hydrated Potassium Sodium Aluminum Silicate)
      • Garronite (Hydrated Calcium Aluminum Silicate)
      • Gismondine (Hydrated Barium Calcium Aluminum Silicate)
      • Gobbinsite (Hydrated Sodium Potassium Calcium Aluminum Silicate)
    • Gmelinite (Hydrated Sodium Calcium Aluminum Silicate)
    • Gonnardite (Hydrated Sodium Calcium Aluminum Silicate)
    • Goosecreekite (Hydrated Calcium Aluminum Silicate)
    • The Harmotome Family:
      • Harmotome (Hydrated Barium Potassium Aluminum Silicate)
      • Phillipsite (Hydrated Potassium Sodium Calcium Aluminum Silicate)
      • Wellsite (Hydrated Barium Calcium Potassium Aluminum Silicate)
    • The Heulandite Family:
      • Clinoptilolite (Hydrated Sodium Potassium Calcium Aluminum Silicate)
      • Heulandite (Hydrated Sodium Calcium Aluminum Silicate)
    • Laumontite (Hydrated Calcium Aluminum Silicate)
    • Levyne (Hydrated Calcium Sodium Potassium Aluminum Silicate)
    • Mazzite (Hydrated Potassium Sodium Magnesium Calcium Aluminum Silicate)
    • Merlinoite (Hydrated Potassium Sodium Calcium Barium Aluminum Silicate)
    • Montesommaite (Hydrated Potassium Sodium Aluminum Silicate)
    • Mordenite (Hydrated Sodium Potassium Calcium Aluminum Silicate)
    • The Natrolite Family:
      • Mesolite (Hydrated Sodium Calcium Aluminum Silicate)
      • Natrolite (Hydrated Sodium Aluminum Silicate)
      • Scolecite (Hydrated Calcium Aluminum Silicate)
    • Offretite (Hydrated Calcium Potassium Magnesium Aluminum Silicate)
    • Paranatrolite (Hydrated Sodium Aluminum Silicate)
    • Paulingite (Hydrated Potassium Calcium Sodium Barium Aluminum Silicate)
    • Perlialite (Hydrated Potassium Sodium Calcium Strontium Aluminum Silicate)
    • The Stilbite Family:
      • Barrerite (Hydrated Sodium Potassium Calcium Aluminum Silicate)
      • Stilbite (Hydrated Sodium Calcium Aluminum Silicate)
      • Stellerite (Hydrated Calcium Aluminum Silicate)
    • Thomsonite (Hydrated Sodium Calcium Aluminum Silicate)
    • Tschernichite (Hydrated Calcium Aluminum Silicate)
    • Yugawaralite (Hydrated Calcium Aluminum Silicate)

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Much information for this page provided by the Mineral Database.

Popular Members of the Silicates Class
 

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