Some common examples of minerals include quartz, graphite, talc and amethyst. Other examples include diamonds, gold, silver, copper, rubies, turquoise, topaz and sulfur. With few exceptions, minerals are objects that are form naturally without the intervention of humans.
Unlike the carbon compounds in living materials such as plants, humans and animals, most minerals are completely inorganic. Minerals are solid objects, which means that they usually do not evaporate, droop or melt. Most minerals are crystalline objects that have a specific atom arrangement and recipe.
There are some unnatural substances that are still called minerals, because until the 1990s, some chemical compounds that formed when artificial materials broke down were classified as minerals, although they would not be classified as such any longer. Mercury is one unique mineral, in that it behaves as a liquid at room temperature. In some areas, however, mercury behaves strictly like a mineral, as it solidifies and forms crystals when subjected to extremely cold conditions.
A few types of minerals, such as graphite and diamonds, are formed from organic compounds. While the majority of minerals are crystalline, some have such tiny crystals that they are undetectable to the naked human eye, and a small number of amorphous mineraloids do not form crystals at all.