Minerals Earth Science PDF

SCIED53: EARTH SCIENCE MINERALS GROUP 7: DELA CRUZ, APRIL BUTIN, ANGEL MAY GONZALES, MAY QUEENCY LAPETAHI, ALICE CLAIRE  OBJECTIVES List the main characteristics that an Earth material must possess to be considered a mineral and describe each. Describe three mechanisms that generate minerals and...

SCIED53: EARTH SCIENCE MINERALS GROUP 7: DELA CRUZ, APRIL BUTIN, ANGEL MAY GONZALES, MAY QUEENCY LAPETAHI, ALICE CLAIRE  OBJECTIVES List the main characteristics that an Earth material must possess to be considered a mineral and describe each. Describe three mechanisms that generate minerals and rocks and which yield compositional structural variations in minerals. List and describe the properties used in mineral identification.  OBJECTIVES Compare and contrast the light silicates with the dark silicates and list four common minerals from each group. To list common nonsilicate minerals and explain it's importance in economy. Minerals any naturally occurring inorganic solid that possesses an orderly crystalline structure and a definite chemical composition that allows for some variation. Mineralogy the study of mineral Minerals Naturally occurring Inorganic Solid at room temperature Regular crystal structure Defined chemical composition. Naturally Ocurring this means they form through geological processes without human intervention. Inorganic it is not derived from living organisms. Solid at room temperature ensures that minerals have a stable, ordered structure and consistent properties. Regular crystal structure a regular crystal structure is fundamental for defining a mineral’s identity, stability, and physical characteristics. Defined chemical compsition a defined chemical composition is essential for accurately identifying, classifying, and understanding minerals.  THE VERY FIRST MINERALS MINED The first minerals mined were Flint flint, and chert, which people Chert fashioned into weapons and cutting tools.  Scimitar Neolithic Flint Tools Flintlock GOLD COPPER SIILVER HEMATITE BRONZE TIN  HOW MINERALS FORM? Crystallization is the process by which atoms are arranged to form a material with crystal structure. In general, minerals can form in two ways: by crystallization of molten material or by crystallization of materials dissolved in water. Magma Is the molten or semi-molten natural material from which all igneous rocks are formed. And lava is magma that reaches the surface. Minerals form as hot magma cools inside earth or as lava hardens on the surface. When these liquids cool to a solid state they form crystals.  Intrusive Extrusive When magma cools When lava cools in deep beneath the the surface it forms surface it forms Extrusive igneous Intrusive Igneous rocks like basalt. rocks just like granite. Geode is a rounded hollow rock that is often lined with mineral crystals. crystals form inside a geode when water containing dissolved materials seeps into a crack or hallow in a rock, slowly crystallization occurs, lining the inside with large crystals. Chemical Precipitation occurs when water containing dissolved minerals evaporates or reacts with other chemical. An example of chemical precipitation is the formation of rock salt (halite). When seawater or saltwater from lakes evaporates, the concentration of dissolved salts increases. Eventually, the solution becomes saturated, and sodium chloride (salt) crystallizes out of the water and forms solid rock salt. Biological Precipitation occurs when organisms, such as bacteria or plants, cause minerals to precipitate from a solution. The most common mineral precipitated by organisms is calcite, or calcium carbonate (CaCO3). Calcite is often precipitated by organisms as a polymorph called aragonite. Polymorphs are crystals with the same chemical formula but different crystal structures. Calcite Aragonite PHYSICAL PROPERTIES OF MINERALS Minerals have definite crystalline structures and chemical compositions that give them unique sets of physical and chemical properties shared by all specimens of that mineral, regardless of when or where they formed. Luster The appearance or quality SUBMETALLIC METALLIC of light reflected from the surface of a mineral is known as luster. Minerals that have the appearance of a metal, regardless of color, are said to have a metallic luster Ability to Transmit Light An optical property used to identify minerals is the ability to transmit light. When no light is transmitted, the mineral is described as opaque; when light, but not an image, is transmitted through a mineral sample, the mineral is said to be translucent. Color Generally the most conspicuous characteristic of any mineral, it is considered a diagnostic property of only a few minerals. Slight impurities in the common mineral quartz, for example, give it a variety of tints, including pink, purple, yellow, white, gray, and even black Streak The color of a mineral in powdered form, called streak, is often useful in identification. A mineral’s streak is obtained by rubbing it across a streak plate (a piece of unglazed porcelain) and observing the color of the mark it leaves Streak Hardness One of the most useful diagnostic properties is hardness, a measure of the resistance of a mineral to abrasion or scratching. This property is determined by rubbing a mineral of unknown hardness against one of known hardness or vice versa. A numerical value of hardness can be obtained by using the Mohs scale of hardness, which consists of 10 minerals arranged in order from 1 (softest) to 10 (hardest), as shown in Cleavage In the crystal structure of many minerals, some atomic bonds are weaker than others. It is along these weak bonds that minerals tend to break when they are stressed. Cleavage (kleiben 5 carve) is the tendency of a mineral to break (cleave) along planes of weak bonding. Not all minerals have cleavage, but those that do can be identified by the relatively smooth, flat surfaces that are produced when the mineral is broken. Fracture Minerals having chemical bonds that are equally, or nearly equally, strong in all directions exhibit a property called fracture. When minerals fracture, most produce uneven surfaces and are described as exhibiting irregular fracture Tenacity The term tenacity describes a mineral’s resistance to breaking, bending, cutting, or other forms of deformation. As mentioned earlier, nonmetallic minerals such as quartz and halite tend to be brittle and fracture or exhibit cleavage when struck. Density Defined as mass per unit volume. Mineralogists often use a related measure called specific gravity to describe the density of minerals. Specific gravity is a number representing the ratio of a mineral’s weight to the weight of an equal volume of water Crystal Shape, or Habit Mineralogists use the term crystal shape, or habit, to refer to the common or characteristic shape of individual crystals or aggregates of crystals. Some minerals tend to grow equally in all three dimensions, whereas others tend to be elongated in one direction or flattened if growth in one dimension is suppressed. A few minerals have crystals that exhibit regular polygons that are helpful in their identification.  Mineral Structures The smooth The precise chemical constituents faces and symmetry possessed by and their arrangement inside a well-developed crystals are mineral are referred to as its surface manifestations of the composition. Inorganic solids that orderly packing of the atoms or are found in nature that have a certain chemical makeup and ions that constitute a mineral’s crystalline form are called minerals. internal structure. Relative sizes and charges of selected ions Ionic radii are usually expressed in angstroms (1 angstrom equals 10-8 cm).  Steno’s Law Law of Constancy of Interfacial Angles, because it applies to all minerals. Because Steno’s Law holds for all minerals, crystal shape is frequently a valuable tool in mineral identification. Steno’s Law Because some faces of a crystal may grow larger than others, two crystals of the same mineral may not have identical shapes. Nevertheless, the angles between equivalent faces are remarkably consistent.  Compositional Variations in Minerals Compositional variations in minerals refer to the differences in chemical composition that can occur within the same mineral species. These variations are influenced by several factors, including the presence of impurities, solid solution processes, ionic substitution, and environmental conditions during the mineral's formation.  Structural Variations in Minerals Structural variations in minerals refer to the differences in the arrangement of atoms or ions within a mineral's crystal lattice. These variations can result in different physical properties, even if the chemical composition of the mineral remains the same. MINERAL GROUPS  Minerals can be classified based on their chemical composition. THE ABUNDANT ELEMENTS IN THE CONTINENTAL CRUST COMMON NONSILICATES MINERAL CARBONATES GROUPS SULFATES HALIDES  Nonsilicates make up only about 8 percent of Earth's crust. They are important economically. Some of the most common nonsilicate minerals belong to one of three classes of minerals: carbonates (CO) sulfates (SO) halides (CI, F, Br.)  THE SILICATES  THE LARGEST MINERAL GROUP WITH 1,000+ VARIETIES MAKING UP NEARLY 90% OF EARTH'S CRUST.  THE BASIC BUILDING BLOCK IS THE SILICA-TETRAHEDRA , COMPOSED OF 4 OXYGEN ATOMS BONDED TO 1 SILICON IN A PYRAMID STRUCTURE.  2 TYPES OF SILICATE MINERALS LIGHT SILICATES DARK SILICATES LIGHT SILICATES Generally light in color Have a specific gravity of about 2.7 (due to the absence/presence of iron and magnesium) Less dense Contains: aluminum, potassium, calcium, and sodium. ORTHOCLASE / K Feldspar Most common mineral group Can form under wide range of temperature and pressures Relatively hard PLAGIOCLASE Feldspar Luster ranges from glassy to pearly Identified by their rectangular shape, smooth, shiny faces.  Only common minerals consist entirely silicon and oxygen 3 dimensional framework is developed hard, resists weathering, and does not have cleavage When developed pure and without interference: it forms hexagonal crystals with pyramid- shaped ends  DIFFERENT VARIETIES OF MILKY (white) SMOKEY (gray) ROSE (pink) QUARTS Sales AMETHYST (purple) CITRINE (yellow-brown) ROCK CRYSTAL (clear)  Light color and has pearly luster Has excellent cleavage in one direction In thin sheets Clear, very shiny, and sparkling Used in the cosmetic industry  Complex minerals and have sheet structure. Products of chemical breakdown (chemical weathering) Make up a large percentage of soil. Generally very fine grained which makes them difficult to identify, unless study microscopically. DARK SILICATES Dark in color Have a greater specific gravity between 3.2-3.6 More dense Contains: Iron and Magnesium  a family of high-temperature silicate minerals is black to olive green in color has a glassy luster and occasionally used as a gemstone called peridot olivine commonly forms small, rounded crystals typically found in basalt, a common igneous rock of the oceanic crust and volcanic areas Used in stell production and sand blasting  group of diverse minerals important components in dark- colored igneous rocks The most common member, augite, is a black, opaque mineral with two directions of cleavage that meet at nearly a 90-degree. -use in geochemical analysis  The most common member: Hornblende - usually dark green to black in color -double chain silicates - In a rock, hornblende often forms elongated crystals - provide insights in rock formations and transformation.  dark, iron-rich mineral possesses a sheet structure that gives it excellent cleavage in one direction. shiny black appearance that helps distinguish it from the other dark ferromagnesian minerals.  Carbonates: CO3 2- 1. calcite, CaCO, (calcium carbonate), 2. dolomite, CaMg(CO), (calcium/magnesium carbonate - Calcite and dolomite are usually found together as the primary constituents in the sedimentary rocks limestone and dolostone. - When calcite is the dominant mineral, the rock is called limestone, while dolostone if dolomite is dominant. COMMON USED AS / IN: road aggregate building stone main ingredient in Portland cement. -Toothpaste - Concrete - Glass HALIDES (Cl, F, Br) AND SULFATES (SO4) 2 Examples: halite and gypsum - Both minerals are commonly found in thick layers that are the last vestiges of ancient seas that have long since evaporated. - important nonmetallic resources Gypsum (CaSO4 2 H₂O), which is Halite is the mineral name for calcium sulfate with water bound common table salt (NaCl). into the structure. >> used as food seasoning and >> fertilizer and as the main constituent in many forms of preserving plaster, chalk. Most nonsilicate mineral classes contain members prized for their economic value. This includes the : OXIDES (O²) Fe2 0 2 Fe3 04 hematite and magnetite (important ores of iron for steel production)  SULFIDES sphalerite (ZnS) (S²) galena (PbS) chalcopyrite(CuFeS2) NATIVE ELEMENTS (Au, Ag, C) gold silver carbon (diamonds)