Rounded nucleus of Hornblend in authigene Hornblend

Category Petrology
Group GSI.IR
Location 21th symposium on geosciences
Holding Date 21 May 2008

      The increasing of two factor, meteoric water and a sudden decrease in pressure (acting together or alone) in addition to in stability in the magma chamber, resulting important chemical and textural changes in hornblend mineral. Hornblend mineral involved a lot of Fe but with increasing temperature and decrease in pressure, it digested and shaped in the form of rounded. After appearance of appropriate condition, it will recrystallize around of rounded nucleus of hornblend. This is due to oxidization condition in magma chamber and extraction of ionic iron (in the form of Fe2+, Fe3+) from the silicate melt have caused important chemical changes in magma chamber. As a result of extraction, two phases (Ilmenite and magnetite) have observed. Consequently Fe% decreased and Mg% increased. In the new chemical condition, a hornblende poor in Fe and enriched in Mg, around previous hornblend (poor in Mg and enriched in Fe) crystallized, which will proved with microprobe analyze.

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