The most valuable rocks are ores. These rocks contain minerals or metals that can be of great commercial value, such as gold, platinum, copper, iron, nickel or silver.Know More
Some elements are found in more than one type of rock, and some rocks contain more than one type of element. Galena, for example, is a major source of lead, but it can also contain silver.
Nickel, a silvery white, shiny metal that has leant its name to an American coin, is found in limonite, which also contains iron. Another nickel ore is pentlandite, which contains iron as well as small amounts of cobalt.
Iron, which is strong, ductile and malleable, is one of the most sought after metals and is inexpensive because it's abundant. This is true even though iron is such a reactive element that it's rarely found in its free state. Among the ores of iron besides those mentioned are hematite, goethite and magnetite. The Earth's core is made of iron, and it's even found in meteors in the form of siderite.
Copper is also found in many types of rocks, especially rocks that are abundant in carbonates, oxides and sulphides. These ores include rocks that have their own esthetic value such as malachite, cuprite and azurite.Learn more in Geology
Rocks come from magma, which is the molten material found within the earth. When magma cools, either above or below the earth's surface, it crystallizes and forms the igneous rocks that can later be changed into metamorphic or sedimentary rocks. Magma, which can be considered molten rock, is referred to as lava when it reaches the earth's surface.Full Answer >
Humans use rocks for a wide variety of purposes, including construction and as a source of valuable minerals located inside the rocks. Additionally, humans use rocks for decoration, recreation and thermal purposes. Humans are not the only organisms that utilize rocks, as plants, animals and fungi use rocks for stability, digestive purposes and as a substrate.Full Answer >
Rocks are formed in three primary ways, and each method produces rocks with different characteristics. Rocks are either classified as sedimentary, igneous or metamorphic, depending on the manner in which they were formed. Most rocks encountered in everyday life are sedimentary, although some igneous rocks, such as granite, are also common.Full Answer >
Rocks are different from minerals in that minerals are single crystalline accumulations of one or more elements, while rocks are solid accumulations of one or more minerals. Rock can either refer to a particular, detached object or, in a general sense, as a synonym for stone, generally referring to a portion of the substance. Individual minerals can be obvious in rocks, as with granite, or microscopic, as with many basalts.Full Answer >