Title: Competency Assessment: (CU1 M1) ANSWER KEY Mineral Identification
Course: SkillsCom GS 106 14.0 > Section: Credit Unit 1 Module 1- Minerals, Rocks, Geologic Time

1. What are the five characteristics of a mineral?

Answer: The five characteristics are that a mineral must be solid, naturally forming, inorganic, have a distinct chemical composition, and a crystalline lattice.

CU 1 M1 Lab #1 Question 1. | Student fully identifies all 5 characteristics of a mineral 4 pts | Student fully identifies 4 characteristics of a mineral 3 pts | Student fully identifies 2 characteristics of a mineral 2 pts | Student fully identifies 2 characteristics of a mineral 1 pts | Insufficients 0 pts

17. All minerals have an orderly internal arrangement of atoms called the crystalline lattice but very few minerals exhibit crystal habit or crystal face. Why is that?

Answer: The main factors that affect crystal growth are pressure, temperature and space for growth. The most important of these factors is space, if minerals do not have enough room to grow into then that will never fully form a perfect crystal habit.

CU 1 M1 Lab #1 Question 17. | Student fully describes reasons for crystal growth inhibition in rocks 4 pts | Student describes reasons for crystal growth inhibition in rocks but misses a few key points 3 pts | Student introduces reasons for crystal growth inhibition but does not discuss importance in rocks 2 pts | Students incorrectly describes crystal growth inhibition and describes importance in rocks 1 pts | Students incorrectly describes crystal growth inhibition and does not describe importance in rocks 0 pts

18. You pick a green mineral and declare to everyone around you that it is in fact olivine without noticing any other characteristics. However, you are in an area with only oceanic sedimentary rocks. What did you do wrong in your declaration? What should you do next time before announcing your identification of a mineral.

Answer: You did not notice your surroundings when identifying minerals and only used color as the basis for your identification. Next time, before announcing your identification

CU 1 M1 Lab #1 Question 18. | Student correctly identifies problem with identification and fully discusses steps needed for correct identification 4 pts | Student correctly identifies problem with identification and discusses steps needed for correct identification but misses a few key points 3 pts | Students correctly identifies problem with identification but does not discusses steps needed for correct identification 2 pts | Students does not identify the problem with identification but does identify some steps needed for correct identification 1 pt | Students does not identify the problem with identification or the steps needed to correct identification. 0 pt

19. You have a beaker, a mineral sample, and a scale. How do you find the density of this mineral?

Answer: To find the density of a mineral using those tools you must first weigh the mineral sample, which will give you mass. Then you need to fill the beaker with water and measure the volume of the water. Then add the mineral sample to the beaker and measure the new volume of the water that has been displaced. Subtract the first volume from the second volume to get the volume of the mineral sample. Divide the mineral sample mass by the mineral sample volume (mass/volume) to find the density.

CU 1 M1 Lab #1 Question 19. | Students correctly identifies how to use all tools and from measurements can correctly derive density mathematically 4 pts | Students correctly identifies how to use all tools and from measurements cannot correctly derive density mathematically 3 pts | Students correctly identifies how to use tools and does not describe how to derive density mathematically 2 pts | Students correctly identifies how to use a single tool and does not describe how to derive density mathematically 1 pt | Students does not identify how to use tools and does not describe how to derive density mathematically 0 pt

20. You’ve got a mineral sample that you are positive is Calcite but you have no hydrochloric acid. What are some other ways you can decipher calcite from say quartz or plagioclase?

Answer: To correctly identify calcite between quartz and plagioclase is best done through hardness test and checking for cleavage and fracture. Calcite has a hardness of 3 and has 3 planes of cleavage, where quartz has a hardness of 7 and fracture and plagioclase has a hardness of 6 and 2 planes of cleavage. Also, you could check calcite for double refraction, which is specific to calcite only. Lastly, you could attempt to use streak, luster and color, though in this case, those mineral properties would not allow one to differentiate between calcite, quartz, or plagioclase.

CU 1 M1 Lab #1 Question 20. | Student correctly identifies several true ways to differentiate calcite from quartz and plagioclase 4 pts | Student correctly identifies several ways to differentiate calcite from other minerals, but not quartz and plagioclase 3 pts | Student correctly identifies a single way to differentiate calcite from quartz and plagioclase 2 pts | Student correctly identifies a single way ways to differentiate calcite from other minerals, but not quartz and plagioclase 1 pt | Student does not identify any ways to identify calcite. 0 pt