Problems with radiometric dating techniques
During the last stage of crystallization, after most of the magma has solidified, the remaining melt will form the minerals quartz, muscovite mica, and potassium feldspar.
Although these minerals crystallize in the order shown, this sequence is not a true reaction series.
Such a large variety of igneous rocks exists that it is logical to assume an equally large variety of magmas must also exist.
However, geologists have found that various eruptive stages of the same volcano often extrude lavas exhibiting somewhat different mineral compositions, particularly if an extensive period of time separated the eruptions.
Lava (properly called magma before it erupts) fills large underground chambers called magma chambers.
A pioneering investigation into the crystallization of magma was carried out by N. At successively lower temperature, other minerals begin to crystallize as shown in Figure 3.6.Bowen also demonstrated that if a mineral remained in the melt after it had crystallized, it would react with the remaining melt and produce the next mineral in the sequence shown in Figure 3.6.