Understanding Rocks and Minerals: Identification Lab Guide

LAB 1: ROCKS AND MINERALS 100 points Due one week from lab start time. LEARNING OUTCOMES At the end of this lab, you will be able to: 1. Understand the difference between a rock and a mineral 2. Identify the 3 different rock groups 3. Evaluate physical characteristics unique to the three rock groups INTRODUCTION A mineral is a naturally occurring, homogenous, crystalline solid that has a definable chemical composition. A mineral usually has the same composition and structure throughout. Liquids and gases are not minerals. Geologists use the word “grain” to define any small, natural solid particle. Some grains are crystals that grew into their present shape, but others are pieces of larger crystals, fragments containing many tiny crystals, or even shards of glass. Crystal faces are distinctive geometric shapes defined by smooth, flat, surfaces. Each face forms at a specific angle relative to its neighbor. We organize minerals based on their color, streak, luster, hardness, specific gravity, fracture, cleavage, and special properties. Rocks are a collection of minerals that are held together in a firm, solid mass. Igneous rocks form when molten rock (magma or lava) cools and solidifies. Sedimentary rocks originate when particles are cemented together, or by precipitation of minerals from water. They often accumulate in layers. Metamorphic rocks result when existing rocks are changed by heat, pressure, or reactive fluids. Each of these types is part of the rock cycle. Through changes in conditions, one rock type can become another rock type. The minerals in a rock may be so tiny that you can only see them with a microscope, or they may be as big as your finger. Many rocks are made of minerals containing silicon and oxygen, the most abundant elements in the Earth’s crust. Rocks are identified primarily by the minerals they contain and by their texture. The following tables and charts will help you identify different rock groups and types of rocks within each group.

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Igneous rocks Reference Tables for Physical Setting/EARTH SCIENCE (2011) Property Definition How to evaluate Grain Size Mineral/crystal size Glassy (non-crystalline), fine (cannot see grains), coarse (large mineral grains) Color Reflected visible light Light, intermediate, or dark Vesicles Voids from air bubbles Open voids permeate rock

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Dark Minerals Estimate % of blackish crystals Metamorphic rocks Refer ence Tables for Physical Setting/EARTH SCIENCE (2011) Property Definition How to evaluate Banding Foliated rock layering characteristic shape Look for layering in the rock, usually different colors. Can be linear (straight) or distorted (wavy) Grain size Dimensions of minerals/rock building blocks Fine to coarse (if grains exist)

Sedimentary rocks Ref erence Tables for Physical Setting/EARTH SCIENCE (2011) Property Definition How to evaluate Clastic Obvious pieces of rocks (clasts) fused into a matrix Observe clast size, mixture (many sizes), coarse, medium (sand), fine (smooth) Chemical origin Formed in place by chemical processes Results in a uniform mineral throughout. Crystalline texture can range from coarse (visible) to fine. Organic origin Formed in place by biological processes Contains fossils (limestone) or black plant material, such as coal or lignite.

PART 1: IDENTIFY ROCKS AND MINERALS [40 pts, 4 pts each] Sample Number Color Grain Size (Fine, Medium, Course etc.) Hardness (1 through 10) Streak Color Other Comments Mineral or rock name 1 White/ clear none 7 No Streak color Crystal crystal 2 Brown/ Tan course/ rough 6+ No streak color Did not bubble Sandstone 3 Black Smooth 3.5 No streak color Did not bubble Basalt 4 Yellowish fine 4 No streak color Did not bubble Slate 5 White Fine 5+ White streak Bubbled Limestone 6 white/ grey/black course 3.5-4 No streak color Bubbled Granite 7 Red- Brownish Medium 6 No streak color Did not bubble Quartziet

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8 White/ Black/Grey course 6+ No streak color Did not bubble Marble 9 White/ Grey Fine 2.5 Grey streak Did not bubble Pumice 10 black/ Green Smooth 3.5 Little bit of a light streak No bubble/layered Chert Laboratory Summary Questions 20 pts 1. What is the difference between a rock and a mineral? [2 pts] A mineral is a natural occurring substance with distinctive chemical and physical properties, composition and atomic structure. Rocks are generally made up of 2 or more minerals, mixed up through geological processes. a. Can a rock be made of minerals? Why or why not? [1.5 pts] Yes a rock can be made up of minerals, in fact most rocks are composed of one or more minerals. This is because a rock is classified by the types and arrangements within the rock to determine its properties and classification. b. Can a mineral be made of rocks? Why or why not? [1.5 pts] No, a mineral cannot be made up of rocks because a mineral is made up of one or more elements together. However, different minerals themselves make up rocks.

2. Describe two unique properties of each rock group and what each tells us about how the rock formed [5 pts each, 15 total]. a. Igneous 1. Igneous rocks have a unique texture based on whether they cool down below or above the earth's surface. 2. Igneous rocks have diverse mineral compositions based on the minerals present in the original magma/lava. 3. Igneous rocks are formed from the solidification of molten magma or lava. b. Metamorphic 1. One unique property is the Regional Metamorphism; it occurs over large areas and is associated with the tectonic plates, which are how mountains are made. 2. Another unique property is contact metamorphism, which occurs when rocks are heated by the intrusion of molten magma. 3. Metamorphic rocks are formed by the combination of pre-existing rocks due to the changes in temperature, pressure, and chemical environment. c. Sedimentary 1. One unique thing about Sedimentary rocks is that a lot of times they will contain fossils, which are preserved remains and traces of ancient organisms. 2. Another unique thing about these rocks is that they have bedding or stratification, which means each layer in this rock will differ in grain size, thickness, composition, and texture. 3. Sedimentary rocks are formed through the accumulation, compaction, and cementation of sediment particles derived from the weathering and erosion of pre- existing rocks.

PART 2: Campus Rock Hunt 40 pts, 8 pts each Name: _____________________________ Section Time: _______________________ Our class has found itself stranded on an unfamiliar island!!! Where are we? How did we get here? What is this land, and how did it form? To survive and interpret information about our new surroundings, we will attempt to categorize the wild and unknown rock species scattered throughout this land (UARK campus but not Gearhart.) We will collect as much information as we can, and then take that information back home (turned in to the lab instructor) after we are rescued. Directions: • Working in groups of up to three (3), record information in a notebook, on paper, or in this document about the rocks you find on your journey. • Your team will need to systematically identify five (5) rocks and/or minerals in the field. • The following information needs to be recorded: 1. The rock or mineral’s location on campus (e.g., building name or GPS coordinates) 2. Grain size (course, fine, or glassy) 3. Color 4. In situ (placed there by nature), or moved there by humans 5. Extra notes and unique observations 6. A photo or sketch of the rock 7. Rock or mineral? If it is a rock, what type? 8. Hypothesized name for each rock/mineral (what you think the rock/mineral is). A hypothesis is not a guess, it is based on the research that you have performed and could be tested further. • Turn your results into the instructor by submitting the assignment on Blackboard. Sample 1 Location Plant Science Building Grain size (course, fine, or glassy) rough Color dark brown In situ (naturally placed) or moved there by humans? naturally placed, or could have been kicked

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Extra Notes Rock or mineral? Rock Hypothesized name for rock or mineral Sandstone Photo or Sketch (insert in table or below it) Sample 2 Location Chemistry building Grain size (course, fine, or glassy) course Color white/gray In situ (naturally placed) or moved there by humans? Looked like it was moved there by humans or thrown. Extra Notes Rock or mineral? Rock Hypothesized name for rock or mineral Granite Photo or Sketch (insert in table or below it) Sample 3 Location Outside of the AFLS building Grain size (course, fine, or glassy) Smooth Color Really dark black In situ (naturally Placed there by humans it was on the sidewalk

placed) or moved there by humans? Extra Notes Basalt is actually the most common rock type in the earths crust. Rock or mineral? Rock Hypothesized name for rock or mineral Basalt Photo or Sketch (insert in table or below it) Sample 4 Location Kappa Sigma House Grain size (course, fine, or glassy) Fine Color white/clear In situ (naturally placed) or moved there by humans? PLaced there by humans in the rockbed Extra Notes Rock or mineral? Rock Hypothesized name for rock or mineral Marble Photo or Sketch (insert in table or below it) Sample 5 Location Science-Engineering Hall

Grain size (course, fine, or glassy) course Color Brown In situ (naturally placed) or moved there by humans? Naturally placed there Extra Notes It was easily scratched so That is how I knew it was limestone Rock or mineral? Hypothesized name for rock or mineral Limestone Photo or Sketch (insert in table or below it)

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Lab 1 Rocks and Minerals (1) (1)

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