WELCOME TO GEOLOGY 333

Transcription

1 WELCOME TO GEOLOGY 333 Earth Materials and the Environment Lab Instructor: Mike Delucia Office Hours: 11 AM-Noon Wed. and 2-3 PM Th. in 70 CAB Lab Overview Lab Overview: Course Content Lab Policies Introduction to Minerals 1

2 Lab Overview: Course Content First five labs involve minerals (two on physical properties, two on mineral ID, one on using petrographic microscope to study mineral thin sections) Five labs involve rock characterization using hand samples and petrographic microscope study of thin sections One soil lab with student presentations of different soil categories One geology field trip to coal-bearing outcrop Two labs involve environmental application (building stones) and powerful technique of mineral analysis (X-ray diffraction) Lab final exam during last lab period Quizzes at beginning of Labs #2-7 Lab Overview Lab Overview: Course Content Lab Policies Introduction to Minerals 2

3 Lab Policies Arrive on time, except for field trip, when you should arrive 5 minutes early. Absences - Contact TA (mdelucia@illinois.edu) before Lab with valid excuse and you can make it up. Otherwise, need note from Emergency Dean to make up missed Lab. Bring to class all mineral and rock Labs (Labs #1-10): Klein + Philpotts - Earth Materials (main class textbook). Bring MacKenzie and Adams book to six Labs involving petrographic microscope (Labs #5-10). Lab Policies Bring to every Lab the printed summaries of Lab notes and Lab Exercises available on Class Web site. All Labs involve an exercise, which must be completed by 11:50 AM unless authorized by TA. Some labs with petrographic microscope require completion outside of scheduled Lab time. Soon you will be able to enter 69 CAB using i-card. Never leave Lab room unlocked; petrographic microscopes are very expensive. Dont bring food or drinks into 69 CAB and dont leave it messy. Dont use Lab room when another class meets (Monday late morning and afternoon, Thursday morning and afternoon). 3

4 Lab Policies Todays Lab begins with 5-minute pretest on chemical principles; it does not count towards your grade. Labs #2-7 begin with 5-minute Quiz, which does count towards your grade. Quizzes cover key concepts from previous week and reading assignment for current week. Lab Overview Lab Overview: Course Content Lab Policies Introduction to Minerals 4

5 Introduction to Minerals Mineral = A naturally occurring, inorganic solid with a crystal structure (ordered arrangement of atoms) and definable chemical composition. NaCl Introduction to Minerals Importance = (1) Economic Resource - in USA every year each person consumes ~10 tons of mineral resources (including metals and non-metals), which are used in industry, agriculture, construction, ceramics and abrasives. 5

6 Introduction to Minerals Importance = (1) Economic Resource - in USA every year each person consumes ~10 tons of mineral resources (including metals + non-metals), which are used in industry, agriculture, construction, ceramics + abrasives. 2) Ingredients of Rock: Rocks are an aggregate of minerals Peridotite in Hand Sample Peridotite in Thin Section 6

7 Introduction to Minerals Mineral Identification = Chemical composition and crystal structure (ordered atomic arrangement) are what make individual minerals unique from other minerals. Composition: Pure Carbon Graphite Diamond Introduction to Minerals Mineral Identification = Usually geologists identify minerals by analyzing their physical properties. Every mineral has a distinct set of physical properties, which are controlled by their composition and crystal structure. 7

8 Lab Overview Lab Overview: Course Content Lab Policies Introduction to Minerals 4 Physical Properties of Minerals that well cover today: 1. Hardness 2. Cleavage 3. Crystal Shape 4. Specific Gravity Well cover several more physical properties next week! 8

9 1. Hardness = Resistance of a mineral to scratching or abrasion. Hard minerals are difficult to scratch, whereas soft minerals are easy to scratch. What determines the hardness of a mineral? 2. Cleavage = The ability of a mineral to break or cleave along parallel flat surfaces called cleavage planes. What determines the cleavage of a mineral? Amphibole Calcite 9

10 Rules of thumb when determining cleavage: Look for flat surfaces that reflect more light and appear shinier than other broken surfaces. Often cleavage appears as a series of surfaces parallel to each other but at different elevations (like stair steps). Parallel cleavage faces on the opposite sides of a sample count as one cleavage plane. Look at one crystal at a time, because different individual crystals may be oriented differently with differently oriented cleavage faces. Six most common mineral cleavage shapes Basal: Cleavage in one direction forming thin sheets, like stack of paper (platy cleavage). Bioite 10

11 Six most common mineral cleavage shapes Prismatic, 2 at 90 : Cleavage in two directions, forming 90 angles and no cleavage in third direction. Feldspar Feldspar top view Six most common mineral cleavage shapes Prismatic, 2 NOT at 90 : Cleavage in two directions, NOT forming 90 angles and no cleavage in third direction. Amphibole 11

12 Six most common mineral cleavage shapes Cubic: Cleavage in three directions, forming 90 angles, like a cube or shoebox. Galena Halite Six most common mineral cleavage shapes Rhombohedral: Cleavage in three directions, NOT forming 90 angles, like a pushed-over cube or shoebox. Calcite 12

13 Six most common mineral cleavage shapes Octahedral: Cleavage in four directions that produces an 8- sided figure (octahedron), which resembles 2 4-sided pyramids joined bottom to bottom. Fluorite Fracture Minerals with fracture means they dont have cleavage. Fracture surfaces are usually rough and irregular, rather than flat, and may appear duller than cleavage faces. Quartz with Fracture Quartz with Conchoidal Fracture 13

14 1/10/15 3. Crystal Shape (Form or Habit): Crystal: Any homogeneous solid with ordered atomic arrangement, may or may not have crystal faces. Crystal Faces: Flat surfaces produced when a mineral forms without obstruction. New minerals form by crystallization from water, gas, or molten rock. If space crowded during crystallization, crystal faces are obstructed by other crystals during formation, preventing true crystal shape from developing. Well-developed crystal faces indicate abundant space during crystallization. Poor crystal shapes indicate limited space during crystallization. 14

15 Common Crystal Shapes 4. Specific Gravity (G) = The ratio of mass of a mineral to the mass of an equal volume of water, i.e.: G = Mineral Density Water Density = Mass of Mineral Mass of Water Volume of Mineral Volume of Water Pure Water Density = 1 g/ml, THEREFORE: G = Mass of Mineral 1 g/ml Volume of Mineral 15

16 Next Weeks Reading Assignment Chap. 4 in Study of Minerals software by Dyar et al. (program is available on any computer in ICS Computer Lab; there are 6 ICS Computer Labs; specific locations given on Class Web site and in syllabus); procedure to access program is on Class Web site in Course Information link and in syllabus, which you will receive in Lecture class tomorrow. Chapter 3 and p in Klein + Philpotts (2013) Earth Materials Dont Forget! Quiz next week over material covered in this lab and next week s reading. QUESTIONS?? 16