Ananya Kundu posted an Question
September 12, 2020 • 13:53 pm 30 points
  • IIT JAM
  • Geology (GG)

What's the difference between feldspar and feldspathoid?

what's the difference between feldspar feldspathoid?

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    Rahul kumar best-answer

    Feldspars (plagioclase, K-feldspar, Albite) form from silica saturated melt whereas feldspathoids (Leucite, Nepheline) form from silica undersaturated melts. Silica saturated melt means enough silica content in melt and silica undersaturated melt means less silica content in melt.

  • Veer vikram singh Best Answer

    Feldspars are common rock forming minerals composed primarily of two solid solution series. 1 Orthoclase Feldspars (KAlSi3O8 ) –Albite ( NaAlSi3O8 ) 2. Albite ( NaAlSi3O8 )– anorthite (CaAl2Si2O8) Feldspars are common minerals in crust and have high silica content 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 not found in rocks containing primary quartz. Feldspathoids reacts with silica to form silica enriched minerals such as feldspars. example of feldspathoids are Leucite KAlSi2O6. nepheline (Na,K)AlSiO4 Reaction between feldspathoids and silica: Leucite + 2SiO2 = Orthoclase KAlSi2O6 + 2SiO2 = KAlSi3O8

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    very good explanation sir

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