Geology Quiz Answers Chapter 4

Chapter 4: ● At which of the following scales would you be most successful in determining the mineral content of a rock? ○ Thin section ● Which of the following are criteria that must be fulfilled for a substance to be considered a mineral? ○ Naturally occurring ○ Inorganic ○ Crystalline solid ● The word that geologists use to describe how grains and minerals are arranged in a rock is ○ Texture ● Which of the following mineral properties can be directly observed by the naked eye, without the need for testing supplies and equipment, and relate to the appearance of the mineral? ○ Color ○ Cleavage/fracture ○ Crystal shape ○ Luster ● Which of the following are tests we can quickly and easily perform (even in the field) to help us identify a mineral? ○ Effervescence ○ Magnetism ○ Hardness ○ Streak ● Match each observation to the geologic scale at which it would be made. ○ Thin section ■ Light passes through mineral crystals; internal structure of mineral crystals is seen ○ Hand specimen ■ Different-colored grains are present; minerals have different colors ○ Cliff face ■ Rock looks homogeneous; rock appears to be one color ● The mineral halite (pictured) has a cubic atomic structure, whereas quartz has a tetrahedron atomic structure that includes one Si atom surrounded by four O atoms, and fluorite has an octahedron atomic structure that includes two oppositely pointing, four-sided pyramids of Ca and F atoms. ● Match the mineral property with its correct description. ○ Crystal shape ■ A mineral that grows unobstructed by its surroundings can have a distinctive geometric form ○ Color ■ This is a useful, but not always reliable, property; very easily identifiable, but a single mineral may occur in several varieties of this property. ○ Cleavage ■ Some minerals break in specific ways (along specific planes) because of their internal arrangement of atoms ○ Luster ■ This is the way light bounces off a mineral; may be earthy, pearly, metallic, silky, etc. ○ Fracture ■ This occurs when a mineral has an atomic arrangement that does not contain cleavage planes along which the mineral breaks. ● What may be said of the mica mineral in the image? ○ The mineral cleaved along one set of planes to split into thin sheets. ○ Bonds between atoms within sheets are stronger than those between atoms linking the sheets ● Match the mineral property with how it is tested. ○ Hardness ■ Use reference minerals and other standardized materials to see which are scratched by an unknown mineral and which are not. ○ Streak ■ Observe color left behind on a porcelain plate when mineral is dragged across it. ○ Effervescence ■ Observe if a dilute HCl solution bubbles when placed on mineral ○ Magnetism ■ Observe if magnet sticks to mineral. ● Match the term with its description. ○ Silica ■ A compound containing only silicon and oxygen in a ratio of 1:2 (SiO 2) ○ Silicon ● ● ● ● ● ● ● ■ The fourteenth element of the Periodic Table; term may also be used to describe a synthetic material used to make computer chips ○ Silicone ■ A synthetic material (often used for grease or caulk) in which carbon is bonded to silicon atoms to keep the material in long chains Light-colored silicate minerals ______. ○ are the most common minerals in the upper part of the continental crust ○ include quartz, potassium feldspar, plagioclase, and muscovite Silicate minerals that are rich in magnesium and iron are ______ colored. ○ Dark What happens at the atomic scale when a mineral cleaves or fractures? ○ If all bonds have the same strength, they may be arranged in such a way that the mineral cleaves along three planes without passing through an atom. ○ If different bonds between atoms have different strengths, the mineral will cleave along the weakest bond directions. ○ If all bonds have the same strength, they may not be arranged in such a way as to allow cleavage planes to form mineral fractures. Match the rock-forming mineral class with its description. ○ Silicates ■ The most important mineral group on Earth; contain silicon and oxygen; example is quartz ○ Carbonates ■ Carbon and oxygen bonded in a triangular arrangement; example is calcite ○ Oxides ■ Oxygen bonded with a metal; example is hematite ○ Halides ■ Contain chlorine or fluorine; example is halite ○ Sulfates ■ Sulfur that is only bonded to oxygen; example is gypsum ○ Sulfides ■ Sulfur bonded with a metal; example is pyrite ○ Native materials ■ Minerals that contain only a single element; example is copper The three most abundant elements in Earth's crust are ______. ○ Oxygen ○ Silicon ○ Aluminum Which of the following terms refers to the compound SiO2? ○ Silica Rank the following by size in order from smallest to largest, with the smallest on the top. ● ● ● ● ● ● ○ Electron ○ Atomic nucleus ○ Single atom of an element ○ Mineral The most common minerals in the upper part of the continental crust are _____-colored silicates. They are felsic in composition, and their color is a direct result of their elemental composition. ○ Light Match the atomic term with its description. ○ Nucleus ■ Part of the atom that contains the protons and neutrons ○ Protons ■ Parts of the atom with a positive electrical charge ○ Neutrons ■ Parts of the atom that do not have a charge ○ Atomic mass ■ Number of positively charged plus neutrally charged particles in an atom ○ Electrons ■ Negatively charged particles in orbit around the nucleus of an atom ○ Electron shells ■ The different energy states of negatively charged atomic particles arranged around the nucleus of an atom Dark-colored silicate minerals ______. ○ include amphibole, pyroxene, olivine, garnet, and biotite ○ form most of the oceanic crust and the mantle ○ are called mafic minerals, as they contain high amounts of Mg and Fe What factors contribute to a water molecule having polarity? ○ Hydrogen atoms are grouped on one side of the oxygen atom. ○ Electrons spend more time around the oxygen atom and give the molecule a negative side and two positive ends on the other side. ○ Oxygen more strongly attracts electrons than hydrogen does. Match the location with its two most common elements. ○ Earth’s crust ■ Silicon and oxygen ○ Universe ■ hydrogen and helium ○ The entire Earth ■ Oxygen and iron Rank the following in order to show the precipitation of halite from water. Place the first event at the top and last event at the bottom. ● ● ● ● ● ● ○ Salty water begins to evaporate ○ As water molecules move out of the liquid state, Na cations and Cl anions become more concentrated and are left behind ○ Na cations and Cl anions become closer to each other and begin to bond ○ Resulting NaCl pairs combine and begin to organize into and ordered structure: a halite crystal What is true of atoms, elements, and minerals? ○ An element is a type of atom that has a specific number of protons. ○ Minerals are composed of chemically bonded elements. ○ An atom is the smallest unit of an element that retains the characteristics of that element. Which of these gemstones is a variety of the mineral corundum? ○ Ruby ○ Sapphire Water molecule images ○ That the atoms in a water molecule are covalently bonded ○ Graphic representations of the water molecule ○ The polarity of a water molecule with respect to its O and H "ends" What gemstone is someone interested in if they are searching for a kimberlite pipe? ○ Diamond Explain the dissolution of halite in water by putting the following steps in the correct order. Place the first event at the top and the last event at the bottom. ○ Halite crystals are immersed in water ○ The positive end of a water molecule becomes attracted to Cl anions, whereas the negative end of a water molecule becomes attracted to Na cations ○ When the attraction of the polar water molecule to various cations and anions is strong enough, it pulls the anions away from the halite crystal ○ Na cations become surrounded by negative sides of water molecules and Cl anions become surrounded by positive sides of water molecules ○ As this process is repeated, the halite crystals are eventually dissolved in water Match the gemstone with its geologic environment of formation. ○ Diamonds ■ Deep under the mantle; high temperature and extremely high pressure; brought to the surface in kimberlite pipes ○ Ruby, sapphire, and emerald ■ In pegmatites that crystallized from magma containing relatively high amounts of water ○ Opal ● ● ● ● ● ■ Not a mineral (does not have orderly crystalline structure); forms in volcanic rocks and some sedimentary rocks with voids, as silicon-rich water fills the voids ○ Pearl and amber ■ Not minerals; form through organic processes Match the gemstone to its description. ○ Ruby ■ The red variety of corundum ○ Peridot ■ The gem variety of the mineral olivine ○ Emerald ■ The green variety of bery ○ Citrine ■ The yellow-orange variety of quartz What are two main ways that geologic minerals are used in society? ○ As a source of elements and compounds that we use to manufacture other products ○ For some of their special properties, like color, density, and resistance to heat or abrasion, etc. Which of these are associated with the formation of diamonds and bringing them to the surface? ○ Kimberlite pipes ○ Very high pressures The formation of many gemstones such as ruby and sapphire are associated with ______ conditions. ○ High temperature ○ High pressure ○ Hot water Match the mineral with its use in society. ○ Quartz ■ May be used for chemical components; the element silicon is used to create computer chips and is mostly derived from this mineral. ○ Hematite ■ May be used for chemical components; iron is the main ingredient in steel and is mostly mined from minerals such as this. ○ Clays ■ May be used for its physical properties; this mineral is used to produce brick, cement, and ceramics. ○ Gypsum ● ● ● ● ■ May be used for its physical properties; sheetrock and plaster products are made from this mineral. Cement is created from processed _____ the most common carbonate mineral; it is obtained from limestone rock. ○ Calcite Match the mineral/mineral group with how it is used, based on its physical properties. ○ Quartz ■ Hardness, transparency, and high silica content help make this mineral good for making glass windows and glass block. ○ Clay ■ Absorbent properties allow it to be used for cat litter. ○ Feldspar ■ Improves hardness and durability of glass; used in ceramics, china, and glass-fiber insulation; this mineral is often mined from granite. ○ Gypsum ■ This mineral, which forms through evaporation, is naturally fire-resistant; used for wallboard, plaster, and cement production. Match the mineral with its chemical use. ○ Halite ■ Sodium is extracted to be used as a pure element. ○ Apatite ■ Phosphorus from this mineral is used in fertilizers, soft drinks, and some televisions. ○ Calcite ■ The chief source of calcium; this mineral is processed into the main ingredient in cement. ○ Copper sulfide materials ■ The metal component is used for electrical wires and in brass and bronze. Which of the minerals/mineral groups provides the red coloring used by artists for thousands of years? ○ Iron-oxide