Mineral Mystery Lab - Student Handout

GEOL 121 Name: Lab Section___L01_______________ MINERAL MYSTERY LAB Learning Objectives At the end of this lab students will be able to: ● Observe characteristics of minerals. ● Describe differences in physical properties of minerals ● Use physical properties to identify minerals. ● Develop and produce a system for identifying different minerals via a flow chart. Introduction Ultimately, geology is about storytelling; we can think of the entire Earth’s history as a book, the pages in the book are filled with stories that we developed by looking at the rocks that form our planet. Minerals that make up those rocks help us identify the rocks, so we can tell their stories. We also use minerals in our lives every day, often without even noticing. Minerals are in your cell phone, your car, your countertops (well, some of our countertops anyway) and even your walls. So, not only do minerals help us tell Earth’s story but they also help make our modern lives possible. Minerals come in all shapes, colors, and sizes but they share common characteristics that we can use to sort them into groups. In this lab, you take on the role of a mineralogist by testing various physical properties, sorting minerals into categories with similar characteristics, and then creating a flowchart to use to identify minerals. 1

Mineral Mystery Lab GEOL 121 Step 1: Search for clues Observe the grid of minerals in front of you. None of them are currently named - that’s okay! Before we get into labeling, let’s take a close look at each of the minerals. Q1 . What are some physical characteristics that multiple minerals share? What are three different ways that you could divide these minerals into 2–3 groups based on those characteristics? Option 1 Luster Group 1 characteristic: Metallic Group 2 characteristic: submetallic Group 3 characteristic (optional): Mineral(s): E, J, H, D, I, K Mineral(s): F, C, G, A, L Mineral(s): Option 2 Density Group 1 characteristic: Heavy Group 2 characteristic: Light Group 3 characteristic (optional): Mineral(s): D, E, I, L, Mineral(s): A, J, K, F, H, G, C Mineral(s): Option 3 Feel Group 1 characteristic: Smooth Group 2 characteristic: Rough Group 3 characteristic (optional): Mineral(s): L, I, J, K, G, C, B, F Mineral(s): D, E, A, H Mineral(s): Once you have come up with three different ways to divide these minerals into groups based on their physical characteristics, compare the groups you made with the other pair of students in your small group. What groups are the same? What groups are different? Is there more than one valid way to group the minerals? 2

Mineral Mystery Lab GEOL 121 Q3 . Compare the following pairs of minerals and list any differences that you notice between the two. Differences in terms of physical characteristics and differences in terms of interaction with tools are both valid! Mineral A Mineral F -Silky -Multi-colored -More Dense -Not as hard (light scratch on glass 5.5 hardness) -Not translucent -Waxy -Single color -Less dense -Harder (scratches glass deeper) - Translucent Mineral B Mineral J - Glassy - 2.5 hardness - Darker color - More dense -Waxy -3.5 hardness - Light colored - less dense Mineral C Mineral G -Greasy -not effervescent -below 3.5 hardness -Silky - Effervescence -below 3.5 hardness Mineral D Mineral H -magnetic -metallic -more dense -3.5 hardness -not magnetic -waxy -Less dense -2.5 hardness 4

Mineral Mystery Lab GEOL 121 Mineral E Mineral I -less dense -Metallic - colorful -3.5 hardness -More dense -Waxy -dark in color -6.5 hardness Mineral H Mineral L -Less dense -3.5 hardness -smooth -more dense -3.5 hardness -rough Again, reconvene with your small group. For each mineral pair, discuss what difference you think will be the most useful for distinguishing between the two minerals. Come to a consensus for each mineral pair within your small group. Circle or highlight that difference in each of the tables above. Q4 . Now put together all of your observations! List 3–5 physical properties for each mineral: 5

Mineral Mystery Lab GEOL 121 Mineral J Glassy Planar cleavage Black/gold 2.5 hardness Mineral K Not dense Orange and white Rough 6.5 hardness Mineral L Rough Dense 3.5 hardness Dark with hints of green Step 2: Identify the suspects Q1 . What did you learn from Step 1? Q2 . Applying your understanding of mineral physical properties, use the following table (which contains the name and physical properties of minerals) to construct a Mineral Identification Flow Chart. Follow the flow chart, answering the questions for each mineral. Place the correct mineral names in the boxes. Quartz SiO 2 Color: colorless, white, pink, any color Streak: white/colorless Luster: glassy Hardness: 7 Conchoidal fracture common Specific Gravity: 2.65 Plagioclase Feldspar NaAlSi 3 O 8 to CaAl 2 Si 2 O 8 in varying proportions Color: white to green-gray Streak: white/colorless Luster: milky to translucent Hardness: 6 Cleavage: good, 2 planes at 90º Striations on cleavage planes Specific Gravity: 2.62–2.75 Amphibole Ca 2 (Mg,Fe(Ca,Na) 2- 3 (Mg,Fe +2 ,Fe +3 ,Al) 5 Si 6 (Si,Al) 2 O 22 (OH) 2 Color: black , dark green, dark brown, dark gray Streak: white/colorless Luster: vitreous to dull Hardness: 6 Cleavage: Imperfect 2 directions at 56° and 124° / uneven Specific Gravity: 3–3.4 7

Mineral Mystery Lab GEOL 121 Halite NaCl Color: colorless Streak: white/colorless Luster: glassy Hardness: 2.5 Cleavage: perfect, 3 planes @ 90º Salty taste Muscovite (mica) KAl 2 (AlSi 3 O 10 )(F,OH) 2 Color : colorless to pale yellow/gold Streak: white/colorless Luster: glassy, milky Hardness: 2–2.5 Specific Gravity: 2.8–2.9 Cleavage: perfect in 1 direction; Thin, elastic sheets of micas Galena PbS Color: gray Streak: gray Hardness: 2.5 Cleavage: good, 3 planes @ 90º Specific Gravity: 7.5 (very dense) Sulfur smell on fresh surfaces Pyrite (fool’s gold) FeS 2 Color: brassy yellow Streak: green-black to black Luster: metallic Hardness: 6–6.5 Specific Gravity: 5.02 Magnetite Fe 3 O 4 Color: dark gray to black Streak: black Luster: metallic Hardness: 5.5-6.5 Specific Gravity: 5.2 Cleavage: none Magnetic Biotite K(Mg,Fe) 3 AlSi 3 O 10 (OH) 2 Color: brown to black Streak: white to gray Luster: pearly to submetallic Hardness: 2.5-3 Specific Gravity: 2.7-3.4 Cleavage: Single perfect cleavage to produce thin flexible sheets or flakes. Calcite CaCO 3 Color: colorless, white, yellow Streak: white/colorless Luster: glassy Hardness: 3 Specific Gravity: 2.71 Cleavage: perfect, 3 planes @ 75º Effervesces in dilute HCl acid Pyroxene (NaCa)(Mg,Fe,Al)(Al,Si) 2 O 6 Color: Usually dark green , dark brown or black Streak: white, greenish white or gray Luster: vitreous (glass-like) Hardness: 5-6 Specific Gravity: 3.2-3.5 Cleavage: Two directions, that meet at nearly right angles (87  and 93  ) Potassium Feldspar KAlSi 3 O 8 Color: typically shades of peach, orange, or red Streak: white Luster: crystals are vitreous (glass-like) to porcelaneous (porcelain-like) Hardness: 6 Specific Gravity: 2.6 Cleavage: One perfect cleavage and one good cleavage, meet at nearly 90  8

Mineral Mystery Lab GEOL 121 Q1. Applying your understanding of mineral physical properties, use flow chart you made in the previous step to identify your 12 unknown mineral specimens. We will identify Mineral A and Mineral B together as a class. Work in pairs and then share your findings with your larger group. Place your answers in the space provided, in the table below. Enter the names of the minerals in the spaces below. Mineral A = Plagioclase Feldspar Mineral E = pyrite Mineral I = Galena Mineral B = muscovite Mineral F = quartz Mineral J = biotite Mineral C = halite Mineral G = calcite Mineral K = Potassium Feldspar Mineral D = Magnetite Mineral H = Amphibole Mineral L = Pyroxene Step 4: Reflection Q1 : What did you enjoy about this lab? Learning about how to describe rocks more accurately Q2 : What was difficult about this lab? The last section – entering the names of the minerals in the blanks Q3 : What questions do you still have about identifying minerals? I still don’t understand the cleavage concept/how to find it. 10