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.
The two best-known igneous rock types are basalt and granite, which have distinctly different compositions and textures. Basalt is the dark, fine-grained stuff of many lava flows and magma intrusions. Its dark minerals are rich in magnesium (Mg) and iron (Fe), hence basalt is called a mafic rock.So basalt is mafic and either extrusive or intrusive.Granite is the light, coarse-grained rock formed at depth and exposed after deep erosion.he main thing about igneous rocks is that they were once hot enough to melt. The following traits are all related to that. 1  Because their mineral grains grew together tightly as the melt cooled, they are relatively strong rocks. 2  They're made of primary minerals that are mostly black, white or gray.