What determines the viscosity of magma m b

Viscosity is fluid resistance. Viscosity depends primarily on the magma composition and temperature. Higher SiO2 (silica) content magmas have higher viscosity than lower SiO2 content magmas (viscosity increases with higher SiO2 concentration in the magma). Viscosity depends on primarily on the composition of the magma, and temperature. Higher SiO2 (silica) content magmas have higher viscosity than lower SiO2 content magmas (viscosity increases with increasing SiO2 concentration in the magma).