Some examples of ferromagnesian minerals in mafic rock include olivine, pyroxene and amphibole. Rocks containing pyroxene and amphibole often also contain feldspar, a non-ferromagnesian mineral.
Olivine is made of fayalite, with a chemical formula of Fe2SiO4, and forsterite, with a chemical formula of Mg2SiO4. Pyroxene can be composed of enstatite (MgSiO3) and ferrosilite (FeSiO3). Igneous amphibole is made of hornblende, which is composed of an iron-magnesium silicate, a calcium-iron-magnesium silicate and an aluminum-iron-magnesium silicate. All of these minerals contain iron and magnesium. Mafic rock is a dark-colored category of igneous rock, the type of rock that forms from solidified magma.Learn More
Rocks are important because geologists use evidence from them to learn about what the Earth was like in the past. They allow scientists to build a historical record of the planet to learn what events occurred before people lived.Full Answer >
Granite is a large-grained igneous rock usually comprised of minerals like feldspar, quartz, mica and amphibole. It varies in color and appearance based on the mineral composition of the rock layers near where it is located. Granite, an igneous rock, is formed by magma cooling beneath the surface.Full Answer >
The study of geology is important for three main reasons: it reveals the deep history of the Earth, informs other sciences, and it is useful for economic purposes. Before geology was a science, the age and development of the Earth were mysterious, and prospecting for minerals was a hit-and-miss business.Full Answer >
Marble is a metamorphic rock. This means that it was formed out of another rock after eons of heat and pressure. Marble is formed out of pure limestone.Full Answer >