The Earth: Resources In The Crust (1960)

[Music] so [Music] this rocky surface is a part of the earth's crust this crust is the earth's outer covering compared to the whole earth the crust is relatively thin it averages about 20 miles in thickness yet man obtains all of his mineral resources from this crust we can group the mineral resources this way metallic minerals such as this iron ore non-metallic minerals such as this sulfur and mineral fuels such as this coal most metallic minerals are found in formations called igneous rock the majority of the non-metallic minerals as well as our mineral fuels are found in sedimentary rock a few non-metallic minerals are found in metamorphic rock metallic minerals are found throughout the world as are the non-metallic minerals and the mineral fuels this copper axe reminds us that metallic minerals were used as long ago as 5000 bc combining copper with tin produced bronze a harder metal but the hardest of the ancient metals was iron although iron was widely used many centuries were to pass before iron came into the extensive use we know today here we see one kind of modern iron mining here the iron ore in the earth's crust lies so close to the surface that it can be dug from open pits like most other minerals iron ore is a chemical compound besides oxygen the ore usually includes unwanted substances mixed with the iron iron ore is sent to a smelting plant where huge furnaces are used to separate the iron from oxygen and other impurities in the ore most of the iron produced in the united states undergoes further treatment which converts it into steel whether used as a delicate watch spring or as a heavy piece of machinery or as a ship's hull the steel that comes from iron ore plays an important part in our everyday life copper one of the ancient metals has been widely used in electrical wiring but today copper is being replaced by aluminum and other newer metals for some purposes aluminum in addition to being lightweight is easy to fabricate into a variety of shapes this is bauxite the ore from which aluminum is extracted bauxite is the most widely distributed metallic compound in the earth's crust aluminum is extracted from its ore by an electrolytic process then the metal aluminum is fabricated into many different products such as cable and sheeting sometimes aluminum is alloyed with another light metal magnesium alloy is used in the manufacture of many strong and lightweight products metallic minerals are distributed throughout the world today most of the world's iron comes from these areas most of the world's copper comes from these areas while the known supplies of aluminum are distributed throughout the world the refining of most metallic minerals requires vast sources of energy fortunately the earth's crust does provide vast sources of energy in the form of mineral fuels such as coal most mineral fuels are found in sedimentary rock it is believed that in this rock once living organisms have been changed into mineral fuels time plus the forces of heat and pressure change the organisms into coal oil and natural gas coal is one of our oldest fuels it can either be mined from surface deposits as in this strip mining operation or from underground mines although coal is becoming less important as a fuel coal is the source of important byproducts such as these drugs coal is no longer our main source of power in highly mechanized countries oil has become an important source of power oil like coal was also formed deep within the earth's crust another mineral fuel natural gas is often found with oil deposits and may have been produced in the oil forming process natural gas flows from wells like this it is then compressed to force it through thousands of miles of pipe so that it may be used to heat our homes as well as factories today the earth's crust is yielding new mineral fuels they are radioactive minerals and contain more energy than man has ever known this atomic reactor uses uranium a new mineral fuel in addition to the mineral fuels and the metallic minerals the earth also provides many non-metallic minerals including many essential building materials granite is an important building material so is clay from which bricks and tiles are made limestone is another building material limestone and clay are the materials from which cement is made cement is the basic ingredient of concrete an important building material common sand is another important non-metallic mineral sand provides the basic ingredient of glass glass is used in great quantities as a building material still another non-metallic mineral sulfur is mined from underground deposits in a very unusual manner hot water and compressed air are pumped underground where they melt the sulfur and force it to the surface the melted sulfur is then allowed to solidify this is an immense block of hardened sulfur later the sulfur is broken up and loaded into box cars most sulfur is destined for the chemical industry another important non-metallic mineral used in industry is salt the ocean is one source of salt millions of years ago ancient shallow seas evaporated leaving large deposits of salt today these deposits of salt are often found underground having been covered by other minerals this gigantic salt mine lying beneath the city of detroit michigan is one of the largest in the world millions of tons of salt are consumed every year salt is essential to the diet of most living creatures including man so salt is one of the most important non-metallic minerals the list of non-metallic minerals is almost endless so it's not surprising to learn that non-metallic minerals such as these make up most of the earth's crust we have seen that within the crust are found three groups of mineral resources these resources will not last forever abandoned mines are a sign that mineral sources can be exhausted but there are methods of conserving the resources in the earth's crust we can use efficient mining techniques in extracting mineral resources from the earth's crust we can process our mineral resources carefully without waste and we can increase our supply of mineral resources through scientific investigation of the earth's crust with wise use the vast resources of the earth's crust will continue indefinitely to supply man with the many materials he needs for the complex world in which he lives [Music] you