Rocks in the crust are mixtures of a few elements including oxygen, silicon, aluminum, iron, and sodium, which combine chemically to form about 2,000 different minerals. Wednesday Rocks are always changing. Pressure, heat, erosion, and other factors are constantly at work, slowly reshaping rock in ways be may not notice over our lifetimes. Igneous rocks were once molten, originating deep in the earth and cooling at different rates. Granite is a common igneous rock found in New England.
Limestone is a common example.
Sedimentary rocks may erode back into sediment, or may be transformed by great heat and pressure into metamorphic rock, like marble or schist. Igneous rock can also be transformed directly into metamorphic rock. Maybe you didn't know that these two minerals are a lot alike. Both of them are formed from the element carbon. Gemstones like diamonds are mineral crystals which have a chemistry and structure that make them look special compared to more common minerals.