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.
Because such slow cooling allows time for large crystals to form, intrusive igneous rock has relatively large mineral crystals that are easy to see. Granite is the most common intrusive igneous rock (Figure 4.12). Figure 4.12: A close-up of a granite sample.he holes make pumice so light that it actually floats in water. The most common extrusive igneous rock is basalt, a rock that is especially common below the oceans (Figure 4.15). Figure 4.13: Extrusive igneous rocks form after lava cools above the surface.