Laboratory 3A_ An Introduction to Minerals_ ESS 101 B Wi 24_ Introduction To Geology And Societal Im

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2/25/24, 6:22 PM Laboratory 3A: An Introduction to Minerals: ESS 101 B Wi 24: Introduction To Geology And Societal Impacts https://canvas.uw.edu/courses/1699809/quizzes/1953709 1/30 Laboratory 3A: An Introduction to Minerals Due Jan 28 at 11:59pm Points 3.5 Questions 9 Available Jan 19 at 9am - Jan 28 at 11:59pm Time Limit None Allowed Attempts 2 Instructions This quiz was locked Jan 28 at 11:59pm. Attempt History Attempt Time Score LATEST Attempt 1 12 minutes 3.5 out of 3.5 Answers will be shown after your last attempt Score for this attempt: 3.5 out of 3.5 Submitted Jan 26 at 2:09pm This attempt took 12 minutes. ATTENTION : You must complete this lab BEFORE you complete Laboratory 3B: Mineral Identification (https://canvas.uw.edu/courses/1699809/quizzes/1953712) . Lab 3A will teach you about the characteristics we use to describe minerals. Lab 3B will have you use the characteristics to identify minerals. If you do not first complete Lab 3A, Lab 3B will be difficult/impossible. Learning Goals By completing this lab, students will learn: The technical definition of a mineral The different physical properties of a mineral and how they form How to use common diagnostic properties to identify a mineral
2/25/24, 6:22 PM Laboratory 3A: An Introduction to Minerals: ESS 101 B Wi 24: Introduction To Geology And Societal Impacts https://canvas.uw.edu/courses/1699809/quizzes/1953709 2/30 Introduction A. Minerals Minerals are the basic building blocks that make up the solid Earth. Therefore, any study of the solid Earth must begin with an understanding of minerals. A mineral, by definition, is a (1) naturally occurring, (2) solid, (3) usually inorganic element or compound with a (4) definite crystalline structure and (5) chemical composition which varies only within specific limits. Common examples are quartz, diamond, garnet, talc, and halite (salt). Some useful hints about what a mineral is/isn't: 1. Although compounds produced in a laboratory can have many of the characteristics of a mineral, they are not naturally occurring and therefore are not minerals. 2. Minerals are solids , therefore liquids and gases are not considered minerals. 3. Nearly all minerals are inorganic, that is, not produced by living organisms. 4. Minerals have a distinct crystalline structure (Figure 3-1) . Each mineral has an orderly, predictable arrangement of atoms. For example, the minerals graphite and diamond are both made of carbon but what makes them unique is a significant difference in the way the atoms are arranged (Figure 3-1). (A mineraloid differs from a mineral in that it lacks crystalline structure (i.e., is amorphous). For example, opal is a mineraloid; it has the same composition as quartz but lacks the crystal structure.) 5. Minerals have a definite chemical composition that can be expressed as a specific chemical formula. Quartz, for instance, is composed of silicon and oxygen and has the formula SiO2. Some minerals have more complex compositions. Garnet's formula, for instance, is A3B2(SiO4)3, where A and B represent a variety of elements such as Ca, Mg, Fe, and Mn. Although the exact composition of garnet can vary, the ratio between A and B is constant — 3 atoms of A for every 2 atoms of B.
2/25/24, 6:22 PM Laboratory 3A: An Introduction to Minerals: ESS 101 B Wi 24: Introduction To Geology And Societal Impacts https://canvas.uw.edu/courses/1699809/quizzes/1953709 3/30 Question 1 0 / 0 pts True False Question 2 0.2 / 0.2 pts Figure 3-1. The atomic structure of (a) diamond and (b) graphite. Diagrammatic inserts show bonding relationships of carbon atoms. In diamond, each carbon atom is strongly bonded (covalent bonds) to four adjacent carbon atoms. In graphite, each carbon atom is strongly bonded to only three neighboring atoms. Strongly bonded atoms in graphite occur in sheets, which are only loosely attached to one another by weak van der Waal forces. Laboratory Honor Statement Cheating or plagiarism of any kind will not be tolerated in ESS 101. This includes copying answers from a friend or classmate, copying answers verbatim found on the internet or other literary sources, or copying any work that may answer the question being asked. Make sure you always use your own words when answering the questions in the homework and cite appropriate references if you use them to help you answer the question. Anyone caught violating the academic code of conduct (https://www.washington.edu/cssc/for-students/academic-misconduct/) will be reported to the UW Academic Misconduct representative. I acknowledge that I have carefully read and understand the above statement regarding the consequences of cheating and plagiarism, and promise to complete my work in this class with honesty and integrity. Answer "True" below supporting your acknowledgement.
2/25/24, 6:22 PM Laboratory 3A: An Introduction to Minerals: ESS 101 B Wi 24: Introduction To Geology And Societal Impacts https://canvas.uw.edu/courses/1699809/quizzes/1953709 4/30 A B These diagrams represent the attomic structures of two solids. The spheres represent atoms that are bonded together. Which structure is a mineral? The unique composition and structure of minerals give them each a unique set of physical properties. Minerals are classified based on these physical properties. During this lab you will become familiar with the important physical properties of minerals and learn how to identify the common rock-forming minerals. Your ability to determine the physical properties of minerals by observation and testing is more important than merely being able to recognize and name minerals. You will be given the opportunity to identify many of these minerals in the future, when we examine rocks. Minerals vs. Rocks A rock is any natural aggregate of minerals, mineraloids, glass, and/or organic particles. For example, granite is a rock composed of several different minerals, rock salt is a rock composed of a single mineral (halite), rock opal is a rock composed of the mineraloid opal, obsidian is a rock composed of volcanic glass, and coal is a rock composed of organic particles. Mineral identification is an important component of geology because the mineral composition of a given rock can tell us a lot about how and where the rock formed. Classification Systems Classification schemes can be subdivided into two principal types, descriptive and interpretive. Descriptive schemes are based on observable physical properties, while interpretive schemes imply a knowledge of how those properties were acquired. We classify minerals based on their physical properties. These properties reflect the chemical elements and crystalline structure of the mineral. Therefore, mineral classification is basically descriptive. When we learn about rocks in future laboratories we will also focus on interpretive classification schemes. Physical Properties of Minerals Because a mineral's physical properties are based on its specific chemical composition and crystalline structure, these properties are unique to each mineral and can be used for identification. The following is a discussion of common properties used for mineral identification. In this week’s two-part lab, you will be learning how to recognize and use diagnostic mineral properties to identify 14 common rock-forming minerals (Figure 3-2). Each mineral has been
2/25/24, 6:22 PM Laboratory 3A: An Introduction to Minerals: ESS 101 B Wi 24: Introduction To Geology And Societal Impacts https://canvas.uw.edu/courses/1699809/quizzes/1953709 5/30 assigned a specimen number for this lab (M1 - M14). In this part of the lab, we will introduce you to specific diagnostic properties that can be used to help identify minerals. In the next part of the lab, you will be asked to use these diagnostic properties to identify the 14 minerals. Figure 3-2. Fourteen common rock-forming minerals (M1 - M14 will be identified in the laboratory this week using their physical (diagnostic) properties. The diagnostic tools we will use to assist us in this identification are shown on the bottom of the image. Luster Luster refers to the way that light interacts with a mineral’s surface. To understand luster, it is helpful to think about some of the basic properties of light. When light reaches a material surface, it can be reflected, absorbed, and/or transmitted through the material (Figure 3-3). All objects that you can see reflect some light, but they may also absorb or transmit some light. The combination of these three properties defines the way that the material appears to our eyes. Reflective materials reflect light back to your eye. However, even a mirror does not reflect all light; some is absorbed or can be transmitted. Absorptive materials absorb some or all light, which changes their color. However, if all light were absorbed, we wouldn’t be able to see the object. Transmissive materials allow light to pass through, like a window. Materials with high transmissivity are called translucent (some light passes through) or transparent (most light passes through), and materials with very low transmissivity are called opaque (little to no light passes through).
2/25/24, 6:22 PM Laboratory 3A: An Introduction to Minerals: ESS 101 B Wi 24: Introduction To Geology And Societal Impacts https://canvas.uw.edu/courses/1699809/quizzes/1953709 6/30 Figure 3-3 . A schematic of the difference between reflection, absorption, and transmission. Luster is classified in the following way: Category Metallic Non-metallic Luster metallic vitreous pearly resinous silky dull Description highly reflective and opaque translucent (highly transmissive) and reflective opaque with an iridescent sheen translucent, but not as reflective as viterous minerals somewhat reflective with a fibrous texture not very reflective, opaque Comparison looks like metal looks like glass looks like a pearl or mollusk shell looks like tree sap or resin looks like silk (has parallel mineral "fibers") looks plain like many earth materials (soil, clay) Example minerals (Figure 3-4) A & B C & D E & F G & H I & J K other minerals with this luster gold, copper, hematite quartz, olivine, plagioclase, amphibole diatomite
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