Exam 4: Igneous Rocks and Intrusive Activity

________is the dominant feldspar in basalt.

________often contain gem- quality crystals of minerals such as beryl and tourmaline and high concentrations of relatively rare elements such as lithium, boron, and beryllium?

What term denotes the larger mineral grains in a porphyritic igneous rock?

All other factors being equal (geothermal gradient, pressure, composition, and heat from other sources such as friction), why is magma generally produced in association with subduction zones as opposed to areas away from subduction zones?

The size of crystals in igneous rocks is generally a function of the rate of cooling. However, within the same rock, crystal size does not necessarily reflect the order of crystallization for individual minerals. Without using Bowen's Reaction Series, how might you determine the order of crystallization of minerals in an individual rock sample? (Hint: Think about the texture.)