Week 1 MineralsIntro-GeorgiaLab - Tagged (1)

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Fullerton College *

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Geology

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Oct 30, 2023

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Week 1: introduction to Minerals Answer the following questions and activities to complete this lab assignment. Read Chapter 7 (skip lab exercises) and answer the following questions: 1. What is the definition of a mineral? A mineral is a naturally occurring, inorganic solid with a definite chemical composition and a characteristic crystalline structure 2. Define what is meant by the “physical properties of a mineral.” Physical properties identify minerals. Briefly define each property a. Color Can be helpful in identifying a mineral but in many cases not a property that is not a very realistic in diagnosing b. Hardness Refers to the resistance of a mineral to being scratched by a different mineral or other material and is a product of the strength of the bonds between the atoms of a mineral. i. Explain the Mohs Hardness Scale and how it is used determine the hardness of a mineral Mohs hardness scale is one of several tests used to document mineral hardness. Minerals are rated on a scale of one through ten with each number correlating to a different mineral type. The mineral that is to be tested is scratched by a mineral from the scale system, and the final result is determined by documenting whether the mineral surface is scratched by a mineral of known hardness c. Crystal form Refers to the geometric shape that a crystal naturally grows into, and is a reflection of the orderly internal arrangement of atoms within the mineral. d. Cleavage Refers to when a mineral is broken with a rock hammer for example and they break or cleave along smooth flat planes. e. Fracture When minerals break irregularly not along cleavage planes. f. Luster Refers to the appearance or reflection of light from a mineral’s surface. i. Vitreous G lassy ii. Silky Luster of a skein of silk or a piece of satin iii. Earthy D ull iv. waxy Similar to a candle’s luster v. Greasy Oily g. Streak Refers to the color left behind on an unglazed piece of porcelain when a mineral is rubbed along its surface. h. Tenacity Refers to the way a mineral resists break- age. If a mineral shatters like glass, it is said to be

brittle (like quartz), while minerals that can be hammered are malleable i. Density and Specific Gravity The ratio of a mineral’s weight to the weight of an equal vol- ume of water. A mineral with a specific gravity of 2 would weigh twice as much as water. j. Reaction to acid Carbonate minerals will effervesce or fizz when acid is applied k. Striations Narrow alternating grooves or furrows and ridges appearing as parallel lines on some minerals l. Magnetism Minerals may be magnetic, and this property is simply tested by seeing if your nail is attracted to a mineral. Activities to be completed: Answer the following questions. The Mineral Table (page 161 in manual) will help you as well as Figure 7.5. Circle or highlight the correct answer. Figures 1-3 1. Review figures 1-3. Answer the following questions (look carefully at each picture for hints to answer the following questions—pretend you are a detective!): A) What is this sample’s hardness? a. harder than glass b. softer than glass but harder than nail c. softer than nail but harder than copper d. softer than copper but harder than a fingernail e. softer than a fingernail B) What is the streak of this sample? a. dark gray streak b. white streak c. reddish brown streak d. pale yellow streak C) What is the luster of this sample? a. non-metallic, vitreous b. non-metallic, earthy c. non-metallic, greasy d. non-metallic, waxy

e. metallic D) Does the bottom figure show that this mineral has cleavage or no cleavage? a. cleavage b. no cleavage E) What is the name of this mineral? a. Calcite b. Gypsum c. Quartz d. Hematite e. Talc f. Pyrite Figure 2 2. Figure 2 is an interesting and common mineral. You will notice that the mineral can have 2 colors. This is because the mineral has Fe (Iron) in it. If it is attacked (or oxidized) by Oxygen it turns red like a nail that has rusted. A) What is the streak of this sample? a. dark gray streak b. white streak c. reddish brown streak d. pale yellow streak B) What is the luster of this sample? May have more than one answer (2 samples)! a. non-metallic, vitreous b. non-metallic, earthy c. non-metallic, greasy d. non-metallic, waxy e. metallic C) What is this sample’s hardness? The white tile in the picture has a Hardness of 6.5 on the Mohs Hardness Scale. Given the following 2 choices, what do you think is the hardness of this mineral? a. from 1-6 b. 6 and greater D) What do you think the cleavage of this mineral is? a. Clearly Shows Cleavage b. Poor Cleavage

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