That is, if you observe the spectrum of a star and can determine the wavelength where the emission peaks (Î»max), you can calculate that starâs temperature. Here is another copy of the plot that we studied in Lesson 3: Figure 4.1: Two-dimensional plot of the spectrum of a blackbody with different temperatures.
Igneous rocks usually contain the most crystals. The longer it takes the magma to cool, the larger the crystals.
Kinds of Igneous Rock. Igneous Rocks are formed by crystallization from a liquid, or magma. They include two types. 1  Volcanic or extrusive igneous rocks wherein the magma cools and crystallizes on the surface of the Earth. 2  Intrusive or plutonic igneous rocks wherein the magma crystallizes at depth in the Earth.f it crystallizes before it reaches the surface it will form an igneous rock at depth called a plutonic or intrusive igneous rock. Because cooling of the magma takes place at a different rate, the crystals that form and their interrelationship (texture) exhibit different properties.