Investigating Minerals, Rocks, and Fossils

Investigating Minerals, Rocks, and Fossils — page 7
INVESTIGATING MINERALs Rocks AND Fossus metallic or nonmetallic Most minerals have a crystalline structure By this definition the resin amber and the fuels coal petroleum and natural gas are not true minerals These substances were formed from organic substances animal or vege table matter that once lived on Earth The important metallic and nonmetal lic mineral beds that are mined today were deposited over long periods of geologic time as a result of such natural phenomena as weathering and erosion Other processes contributing to the concentration of minerals in the earth are sedimentation precipitation and evaporation of water bodies as well as the circulation of groundwater Minerals are essential to the life of plants and animals Most plants get minerals from the soil Animals including humans obtain them from plants vegetables and fruits or from the milk eggs and meat of plant eating animals THE ABUNDANCE OF Rocks Rock makes up the solid crust of Earth Beneath the crust are pockets of molten rock called magma Certain hard substances formed from the remains of animals and 12