The sulfide minerals, typically containing iron and nickel, may also contain relatively high concentrations of platinum, palladium, and other minor metals. So, determining the source of the fluid and of the ore elements is often difficult or impossible. The photo is 8 cm across, 9.56 Cassiterite (SnO2) from Bohemia. Australia produces about a quarter of the worlds aluminum, and Zaire half the cobalt. We call all these deposits Mississippi Valley type (MVT) deposits. In Figure 9.42, the sphalerite is almost gemmy. Consequently, the concentrations of sulfur and other minor elements increase in remaining melt. Section 9.3.3.1, later in this chapter, gives more detailed information about placers. It is a very slow process, like the flux method. Meteorites also contained a small amount of nickel that improved metal properties. 
9.47 Clear spinel, gemstonemagnetism.com Most gold and other precious metal ores contain very fine subhedral metal grains, often microscopic. The Czochralski process can produce 40 cm, or longer, ruby boules. The overall red color is because the chert contains inclusions of hematite. This price difference exists because the natural processes that concentrate most commonly used metals are much more common than the processes that concentrate gold, so there are fewer high-quality gold deposits than there are other kinds of deposits. 9.37 Bornite is brown to copper red when fresh but easily tarnishes, 9.38 Covellite from Butte, Montana space holder, 9.39 Azurite (blue) and malachite (green) from Bisbee, Arizona. This ore, like many Witswatersrand ores, is quite radioactive. The table contains some examples. 4.3 cm tall, 9.58 Millimeter wide pyrolusite (MnO2) dendrites on limestone. The four photos below (9.59 through 9.62) show gemmy examples of emerald, aquamarine, heliodor, and morganite that could be cut to make colorful gemstones. Note that the orpiment contains a small amount of orange realgar; their compositions are nearly identical. This sample is mostly green fluorite, but also contains silver-gray cubes of galena and white and salmon-colored calcite. 9.27 Platinum nuggets, James St. John, Wikimedia Commons Other elements and minerals that exist only in small amounts and have uneven distributions, are equally vital. Some areas near black smokers contain sulfide ooze that might, perhaps, be picked up with a vacuum. The photos below show examples of galena (Figure 9.34), molybdenite (Figure 9.35), and stibnite (Figure 9.36). The table seen here lists the more important species. Fluorite (CaF2) is common but has little economic value. Phone: +46 18 17 90 00E-mail: [email protected], Geological information for mineral exploration. Although common beryl has no value as a gem, it is sometimes mined as a beryllium ore mineral. For example, although aluminum is found in many common silicates, tight bonding makes producing metallic aluminum from silicates uneconomical. In Figure 9.41, two prominent calcite crystals accompany the sphalerite, which has a characteristic brown resinous appearance. Thus, the largest and most easily produced mines control market prices. The United States, like many other countries, has enacted laws to limit the damage caused by mining. But they typically also contain other elements including sulfur, nickel, and less common metals such as platinum, palladium, and chromium. The yellow grains are gold, and the black material is uraninite. Australia contains many large iron mines where hematite is the main ore mineral. The small gray triangular diagram in the top of Figure 9.46 depicts the Cu-Fe-S system. Figure 9.96 shows an iron mine at Tom Price in Western Australia. When exposed to oxygen rich-groundwaters, or to the atmosphere at Earths surface, they easily oxidize or break down in other ways. This mine has produced about 10 million carats of rough diamond since it began operations in 2003. The photo is 11.2 cm across, 9.52 Specular hematite (Fe2O3) with quartz. 9.6 Skiriotissa Copper Mine, MeanStreets, Wikimedia Commons It was not until 1886 that significant production began. Cassiterite, tin oxide, is shown in Figure 9.56. Common skarn minerals include calcite and dolomite, and many Ca-, Mg-, and Ca-Mg-silicates. The tin is in cassiterite (SnO2) that derived from the weathering of nearby granites. Fire is most notable in clear gemstones and may be completely masked in strongly colored stones. Despite industrys claims, however, mining always has a cost to the environment. Typical banded iron formation contains repeating layers of black to silver iron oxide (magnetite), and red chert (microcrystalline quartz). Chapter 7 discussed the formation of laterites and bauxites. But they are also incorporated into grinding wheels, saw blades, and drill bits used to manufacture products from very hard materials. For example, the average crustal abundance of chromium is about 0.01 wt %. Black smokers occur at all mid-ocean ridges and mid-ocean ridge ores are potentially minable. Why did this happen? These deposits are associated with mafic and ultramafic magmas but not, generally, with felsic magmas, because felsic magmas are so viscous that they cool and crystallize before dense minerals can settle. Those in light blue are 3-mineral fields any composition that plots within them will contain three sulfides. Kimberlites, named after the town of Kimberly, South Africa, where they were first described, are volcanic rocks that originate in Earths mantle. Figure 9.55 shows ilmenite, iron titanium oxide. The deposits, which may form centimeters-, or meters-thick layer called a cumulate, are often entirely, or nearly entirely, composed of sulfide minerals. Figures 3.2 and 3.42 (Chapter 3) show other views of golden pyrite. Only eight countries produce lithium, and most of it comes from only three countries. Slate is formed by compaction and occurs as igneous, metamorphic (slate) and sedimentary rock (shale). 9.72 The Logan sapphire in the Field Museum of Natural History, Washington DC. 9.94 Placer gold, James St. John, Wikimedia Commons The smokers cover huge regions of the ocean floor and did so in the past. CZ can have just about any color and so is a common simulant for other, darker-colored, gems as well. Dark colored oxides can be particularly difficult to tell apart, especially because the same mineral can have many different appearances. A mixture of chemicals including those needed to make the desired mineral and others to act as the flux is ground together and heated above its melting point. The other colored stones are generically called sapphire. Because of diamonds great hardness, industrial diamonds have many important uses. Applications: lubricants, pencils, batteries, sealants, steel manufacture, heat insulation, light-weight materials, and more. Most gems are natural materials; they can be either minerals or nonminerals. The moneymaking metals are mostly copper and zinc, but silver, gold, lead, and other metals are important too. When miners reached a zone of pyrite in 1889, the mining slowed because it was not known how to extract gold from sulfides at the time. By heating an inclusion slowly and measuring the temperatures at which any gas bubble disappears and salts dissolve, ore petrologists can often determine the conditions under which an ore deposit formed. Figures 3.51 (Chapter 3) limonite These pipes are the most important source of diamonds today. The photo of chalcopyrite below (Figure 9.33) shows multiple colors due to tarnishing. Disseminated deposits produce most of the worlds diamonds, copper, and molybdenum and also large percentages of the available tin, silver, and mercury. Silicate minerals, although common, are generally poor ore minerals and are not included in the table. Oxides and hydroxides also are distinct from carbonates, sulfates, and other ionic minerals that often have relatively high solubilities in water. Skarns account for nearly three quarters of the worlds tungsten production. Instead they are rich in ore minerals that can be processed relatively inexpensively to isolate desired components. So, pegmatites are often mined for minerals rich in boron, cesium, lithium, molybdenum, niobium, tantalum, tin, tungsten, or other elements. For example, Figure 9.9 (below) shows the many minerals that provide elements that are in a smart phone. So, the denser sulfide minerals will, over time, begin to sink, as shown in Figure 9.76 above. These include mineral deposits of the Southeast Missouri Lead District and related deposits in Iowa, Wisconsin, and Illinois. The resulting deposits are in pods or sheets within sedimentary rock layers that, in places, contain nearly 100% ore. Those same metals and many others are key parts of a seemingly infinite number of products. Sulfide minerals (such as pyrite) contain one or several metallic elements and sulfur as the only nonmetallic element. Oxides including magnetite (Fe3O4), ilmenite (FeTiO3), and chromite (FeCr2O4) may settle and collect at the bottom of a magma chamber, too. The quadrilateral shows seven minerals. Consider the push to expand the use of electric vehicles (EVs). Sedimentary ore deposits also form by chemical precipitation; banded iron formations (BIF), found in Precambrian shields, are examples. Australia dominates the world iron market, producing 36% of all iron ore. Brazil and China each produce about 16%. Many ore bodies, for example, are rich in sulfide minerals. In the 18th century, people used bone ash as a source of phosphorus, created by roasting the bones of animals to liberate contained phosphorus. Agate, opal, chalcedony, and onyx may be tumbled in a cylinder with a polishing/abrading agent. For example, some flat sedimentary rocks in the interior of the United States have strata of limestone that contain ore minerals. They occur in an area about 100 km by 40 km. We mine industrial minerals such as halite, gypsum, clays, calcite, asbestos, micas, and zeolites to make salt, plaster, ceramics, construction materials, electronic components, chemical filters, and many other things. Egyptians mined native metals, including gold, silver, and copper, from stream beds as early as 3700 to 3000 BCE. Cobalt supplies are even more limited. 9.55 Ilmenite, Modris Baum, Wikimedia Commons The largest pillow structure is about 65 cm in long dimension. It is not the composition of gems that makes them valuable, but rather their appearance. If a region contained abundant amounts of copper, silver, tin, or gold, and later iron, it soon became populated and prosperous. Oxidation can alter the original minerals color or texture. We include a photo of azurite and malachite here (Figure 9.39) because of the color similarity to the other two minerals. An ore deposit is a mineral deposit that can be produced to make a profit. They also accuse many mining opponents of having a NIMBY (not in my backyard) mentality. The Witwatersrand deposits are paleoplacer deposits, meaning that they were placers when originally deposited. Sulfides have greater densities than silicate minerals and the mafic or ultramafic melts. Iron is combined with the metals neodymium and boron to make magnets that are part of the microphone and speaker. Most pegmatite mines make their money from mineral specimens and gems rather than from the ore minerals they contain. After the melt solidifies, water or other reagents remove the flux, leaving the desired crystals. Claim holders have the right to purchase the surface and mineral rights at very low cost through a process called patenting, often at $5 an acre or less. Electricity passing through the graphite heats the material to temperatures at which crystals will grow. Thus, all ore deposits are mineral deposits, but the reverse is not true. An industrial mineral is defined by its physical properties, such as fibrosity, insulation capacity, density, hardness, and so on. 9.20 Pillow basalts near Sudbury, Ontario. As shown in the table below, some important elements make up very small percentages of Earths crust; nevertheless, natural processes concentrate them in particular minerals and in particular places. This mine has historically been the largest producer of molybdenum in the world. The area was restored and is now used for picnicking, walking and cycling. 9.31 Pyrite crystals from Huanzala, Peru space holder, 9.33 Tarnished chalcopyrite space holder space holder space holder.
9.47 Clear spinel, gemstonemagnetism.com Most gold and other precious metal ores contain very fine subhedral metal grains, often microscopic. The Czochralski process can produce 40 cm, or longer, ruby boules. The overall red color is because the chert contains inclusions of hematite. This price difference exists because the natural processes that concentrate most commonly used metals are much more common than the processes that concentrate gold, so there are fewer high-quality gold deposits than there are other kinds of deposits. 9.37 Bornite is brown to copper red when fresh but easily tarnishes, 9.38 Covellite from Butte, Montana space holder, 9.39 Azurite (blue) and malachite (green) from Bisbee, Arizona. This ore, like many Witswatersrand ores, is quite radioactive. The table contains some examples. 4.3 cm tall, 9.58 Millimeter wide pyrolusite (MnO2) dendrites on limestone. The four photos below (9.59 through 9.62) show gemmy examples of emerald, aquamarine, heliodor, and morganite that could be cut to make colorful gemstones. Note that the orpiment contains a small amount of orange realgar; their compositions are nearly identical. This sample is mostly green fluorite, but also contains silver-gray cubes of galena and white and salmon-colored calcite. 9.27 Platinum nuggets, James St. John, Wikimedia Commons Other elements and minerals that exist only in small amounts and have uneven distributions, are equally vital. Some areas near black smokers contain sulfide ooze that might, perhaps, be picked up with a vacuum. The photos below show examples of galena (Figure 9.34), molybdenite (Figure 9.35), and stibnite (Figure 9.36). The table seen here lists the more important species. Fluorite (CaF2) is common but has little economic value. Phone: +46 18 17 90 00E-mail: [email protected], Geological information for mineral exploration. Although common beryl has no value as a gem, it is sometimes mined as a beryllium ore mineral. For example, although aluminum is found in many common silicates, tight bonding makes producing metallic aluminum from silicates uneconomical. In Figure 9.41, two prominent calcite crystals accompany the sphalerite, which has a characteristic brown resinous appearance. Thus, the largest and most easily produced mines control market prices. The United States, like many other countries, has enacted laws to limit the damage caused by mining. But they typically also contain other elements including sulfur, nickel, and less common metals such as platinum, palladium, and chromium. The yellow grains are gold, and the black material is uraninite. Australia contains many large iron mines where hematite is the main ore mineral. The small gray triangular diagram in the top of Figure 9.46 depicts the Cu-Fe-S system. Figure 9.96 shows an iron mine at Tom Price in Western Australia. When exposed to oxygen rich-groundwaters, or to the atmosphere at Earths surface, they easily oxidize or break down in other ways. This mine has produced about 10 million carats of rough diamond since it began operations in 2003. The photo is 11.2 cm across, 9.52 Specular hematite (Fe2O3) with quartz. 9.6 Skiriotissa Copper Mine, MeanStreets, Wikimedia Commons It was not until 1886 that significant production began. Cassiterite, tin oxide, is shown in Figure 9.56. Common skarn minerals include calcite and dolomite, and many Ca-, Mg-, and Ca-Mg-silicates. The tin is in cassiterite (SnO2) that derived from the weathering of nearby granites. Fire is most notable in clear gemstones and may be completely masked in strongly colored stones. Despite industrys claims, however, mining always has a cost to the environment. Typical banded iron formation contains repeating layers of black to silver iron oxide (magnetite), and red chert (microcrystalline quartz). Chapter 7 discussed the formation of laterites and bauxites. But they are also incorporated into grinding wheels, saw blades, and drill bits used to manufacture products from very hard materials. For example, the average crustal abundance of chromium is about 0.01 wt %. Black smokers occur at all mid-ocean ridges and mid-ocean ridge ores are potentially minable. Why did this happen? These deposits are associated with mafic and ultramafic magmas but not, generally, with felsic magmas, because felsic magmas are so viscous that they cool and crystallize before dense minerals can settle. Those in light blue are 3-mineral fields any composition that plots within them will contain three sulfides. Kimberlites, named after the town of Kimberly, South Africa, where they were first described, are volcanic rocks that originate in Earths mantle. Figure 9.55 shows ilmenite, iron titanium oxide. The deposits, which may form centimeters-, or meters-thick layer called a cumulate, are often entirely, or nearly entirely, composed of sulfide minerals. Figures 3.2 and 3.42 (Chapter 3) show other views of golden pyrite. Only eight countries produce lithium, and most of it comes from only three countries. Slate is formed by compaction and occurs as igneous, metamorphic (slate) and sedimentary rock (shale). 9.72 The Logan sapphire in the Field Museum of Natural History, Washington DC. 9.94 Placer gold, James St. John, Wikimedia Commons The smokers cover huge regions of the ocean floor and did so in the past. CZ can have just about any color and so is a common simulant for other, darker-colored, gems as well. Dark colored oxides can be particularly difficult to tell apart, especially because the same mineral can have many different appearances. A mixture of chemicals including those needed to make the desired mineral and others to act as the flux is ground together and heated above its melting point. The other colored stones are generically called sapphire. Because of diamonds great hardness, industrial diamonds have many important uses. Applications: lubricants, pencils, batteries, sealants, steel manufacture, heat insulation, light-weight materials, and more. Most gems are natural materials; they can be either minerals or nonminerals. The moneymaking metals are mostly copper and zinc, but silver, gold, lead, and other metals are important too. When miners reached a zone of pyrite in 1889, the mining slowed because it was not known how to extract gold from sulfides at the time. By heating an inclusion slowly and measuring the temperatures at which any gas bubble disappears and salts dissolve, ore petrologists can often determine the conditions under which an ore deposit formed. Figures 3.51 (Chapter 3) limonite These pipes are the most important source of diamonds today. The photo of chalcopyrite below (Figure 9.33) shows multiple colors due to tarnishing. Disseminated deposits produce most of the worlds diamonds, copper, and molybdenum and also large percentages of the available tin, silver, and mercury. Silicate minerals, although common, are generally poor ore minerals and are not included in the table. Oxides and hydroxides also are distinct from carbonates, sulfates, and other ionic minerals that often have relatively high solubilities in water. Skarns account for nearly three quarters of the worlds tungsten production. Instead they are rich in ore minerals that can be processed relatively inexpensively to isolate desired components. So, pegmatites are often mined for minerals rich in boron, cesium, lithium, molybdenum, niobium, tantalum, tin, tungsten, or other elements. For example, Figure 9.9 (below) shows the many minerals that provide elements that are in a smart phone. So, the denser sulfide minerals will, over time, begin to sink, as shown in Figure 9.76 above. These include mineral deposits of the Southeast Missouri Lead District and related deposits in Iowa, Wisconsin, and Illinois. The resulting deposits are in pods or sheets within sedimentary rock layers that, in places, contain nearly 100% ore. Those same metals and many others are key parts of a seemingly infinite number of products. Sulfide minerals (such as pyrite) contain one or several metallic elements and sulfur as the only nonmetallic element. Oxides including magnetite (Fe3O4), ilmenite (FeTiO3), and chromite (FeCr2O4) may settle and collect at the bottom of a magma chamber, too. The quadrilateral shows seven minerals. Consider the push to expand the use of electric vehicles (EVs). Sedimentary ore deposits also form by chemical precipitation; banded iron formations (BIF), found in Precambrian shields, are examples. Australia dominates the world iron market, producing 36% of all iron ore. Brazil and China each produce about 16%. Many ore bodies, for example, are rich in sulfide minerals. In the 18th century, people used bone ash as a source of phosphorus, created by roasting the bones of animals to liberate contained phosphorus. Agate, opal, chalcedony, and onyx may be tumbled in a cylinder with a polishing/abrading agent. For example, some flat sedimentary rocks in the interior of the United States have strata of limestone that contain ore minerals. They occur in an area about 100 km by 40 km. We mine industrial minerals such as halite, gypsum, clays, calcite, asbestos, micas, and zeolites to make salt, plaster, ceramics, construction materials, electronic components, chemical filters, and many other things. Egyptians mined native metals, including gold, silver, and copper, from stream beds as early as 3700 to 3000 BCE. Cobalt supplies are even more limited. 9.55 Ilmenite, Modris Baum, Wikimedia Commons The largest pillow structure is about 65 cm in long dimension. It is not the composition of gems that makes them valuable, but rather their appearance. If a region contained abundant amounts of copper, silver, tin, or gold, and later iron, it soon became populated and prosperous. Oxidation can alter the original minerals color or texture. We include a photo of azurite and malachite here (Figure 9.39) because of the color similarity to the other two minerals. An ore deposit is a mineral deposit that can be produced to make a profit. They also accuse many mining opponents of having a NIMBY (not in my backyard) mentality. The Witwatersrand deposits are paleoplacer deposits, meaning that they were placers when originally deposited. Sulfides have greater densities than silicate minerals and the mafic or ultramafic melts. Iron is combined with the metals neodymium and boron to make magnets that are part of the microphone and speaker. Most pegmatite mines make their money from mineral specimens and gems rather than from the ore minerals they contain. After the melt solidifies, water or other reagents remove the flux, leaving the desired crystals. Claim holders have the right to purchase the surface and mineral rights at very low cost through a process called patenting, often at $5 an acre or less. Electricity passing through the graphite heats the material to temperatures at which crystals will grow. Thus, all ore deposits are mineral deposits, but the reverse is not true. An industrial mineral is defined by its physical properties, such as fibrosity, insulation capacity, density, hardness, and so on. 9.20 Pillow basalts near Sudbury, Ontario. As shown in the table below, some important elements make up very small percentages of Earths crust; nevertheless, natural processes concentrate them in particular minerals and in particular places. This mine has historically been the largest producer of molybdenum in the world. The area was restored and is now used for picnicking, walking and cycling. 9.31 Pyrite crystals from Huanzala, Peru space holder, 9.33 Tarnished chalcopyrite space holder space holder space holder.