Lava Vesuvius between May 14 and June 4, 1737. Serao described "a flow of fiery lava" as an analogy to the flow of water and mud down the flanks of the volcano following heavy rain. The composition of almost all lava of the Earth's crust is dominated by silicate minerals, mostly feldspars, olivine, pyroxenes, amphiboles, micas and quartz. Igneous rocks, which form lava flows when erupted, can be classified into three chemical types: "felsic", "intermediate", and "mafic" (four if one includes the super-heated "ultramafic"). These classes are primarily chemical, however, the chemistry of lava also tends to correlate with the magma
Archean felsic volcanic rocks composition of Archean felsic volcanic rocks are in the calc-alkaline series. Such magmatic series indicates thatfractional crystallisation of magma occurs during cooling. Low magnesium and iron content in the rock and forms dacite or rhyolite. Magma is a mixture of various minerals. When minerals crystallise from the molten magma, they are progressively removed and dissociated from the melt. The last proportion of the melt is strongly fractionated, causing richness in quartz and feldspars that make the volcanic rocks felsic. Dacite and rhyolite are characterised by high silica (SiO) content from 62 to 78 wt%. The average composition of felsic volcanic