• Source: Feldspathoid

The feldspathoids are a group of tectosilicate minerals which resemble feldspars but have a different structure and much lower silica content. They occur in rare and unusual types of igneous rocks, and are usually not found in rocks containing primary quartz. A notable exception where feldspathoids and quartz-bearing rocks are found together is the Red Hill Syenite.
Foid, a contraction of the term feldspathoid, is applied to any igneous rock containing up to 60% modal feldspathoid minerals. For example, a syenite with significant nepheline present can be termed a nepheline-bearing syenite or nepheline syenite, with the term nepheline replaceable by any foid mineral. Such terminology is used in the Streckeisen (QAPF) classification of igneous rocks.




Feldspathoid minerals


Afghanite – Tectosilicate mineral
Analcime – Tectosilicate mineral
Cancrinite – Feldspathoid mineral
Kalsilite – Vitreous white to grey feldspathoidal mineral
Leucite – Potassium and aluminium tectosilicate mineral
Nepheline – Silica-undersaturated aluminosilicate mineral
Petalite – Silicate mineral, used in ceramic glazing
Sodalite Group
Hauyne – Silicate mineral
Lazurite – Alumino-silicate mineral whose blue colour is due to a sulfide species and not copper
Nosean – tectosilicate mineralPages displaying wikidata descriptions as a fallback
Sodalite – Blue tectosilicate mineral
Tugtupite – tectosilicate mineralPages displaying wikidata descriptions as a fallback




References

Kata Kunci Pencarian:

• Diagram QAPF
• Lazuardi
• Feldspathoid
• Gabbro
• Diorite
• Nepheline
• Trachyte
• Essexite
• List of rock types
• QAPF diagram
• Mineral
• Latite