Basalt

                                                       Basalt


What Type of Rock Is It? Igneous
What Does It Look Like? Basalt is dark grey to black. When exposed to the weather, it may turn yellow or brown on its surface. Basalt is fine grained rock You may or may not be able to see crystals with a hand magnifier. The crystals are often microscopic. Basalt is a hard, tough rock. It is difficult to break. Sometimes, basalt contains gas bubbles. It is then called vesicular basalt.
What Minerals Make Up the Rock? plagioclase feldspars, augite, hypersthene, olivene

How Was It Formed? Basalt is a volcanic rock. It is formed from a magma that is rich in iron and magnesium, and poor in silica (quartz). The magma erupts from a volcano or a fissure (a crack in the earth's surface) as lava. Because the lava cools rather quickly, basalt is fine grained. there is not time enough for the grains to become larger.