Page 103 - Laboratory Manual in Physical Geology

ACTIVITY Mineral Identification Procedures
Obtain a set of mineral samples and analysis tools accord-
3.4 Mineral Identification ing to your instructor’s instructions. For each sample, fill
and Uses in the Activity 3.3 tear-out worksheet using the procedures
provided below.
THINK How and why do people study 1. Record the sample number or letter .
About It minerals? How do you personally 2. Determine and record the mineral’s luster as metallic

depend on minerals and elements (M) or nonmetallic (NM)
extracted from them?
A. Metallic (M): mineral is opaque, looks like metal

or sort of like metal)
OBJECTIVE Identify common minerals on the basis of

their properties and assess how you depend on them. B. Nonmetallic (NM): e.g., vitreous (glassy, glossy
reflection), waxy, pearly, earthy/dull, greasy
PROCEDURES

3. Determine and record the mineral’s hardness
1. Before you begin , read the introduction and

mineral identification procedures below. Your ( FIGS. 3.8 , 3.9 ): give a hardness range, if possible.
instructor will provide laboratory equipment, but 4. Determine and record the mineral’s cleavage (if

this is what you will need to bring to lab: present, FIGURES. 3.10 – 3.16 ) and fracture (if present,

___ Activity 3.4 Worksheets (pp. 105 – 108 ) and FIGURE 3.10 ). For cleavage, determine number of
pencil cleavage directions or name, if possible ( FIGURE 3.12 ).

2. To complete the activity, follow your instructor’s 5. Determine and record the mineral’s color (fresh

directions about where to obtain a set of mineral surface) and streak (using a streak plate).
analysis tools and mineral samples and any Minerals harder than 6.5 will scratch the streak
additional procedures for completing Worksheet 3.4 plate, so no streak can be determined for them.
(which you will also need for Activity 3.5).
6. Determine and record other notable properties
3. When you have completed your worksheets , like these:

reflect on how you depend on each of the minerals

that you identified. What did you learn about how A. What is the mineral’s tenacity : brittle, elastic,
you depend on minerals? Be prepared to discuss this malleable, or sectile (can be carved with a knife)?

question and your mineral identifications. Save your B. Does the mineral sample display magnetic

Activity 3.4 worksheets to complete Activity 3.5. attraction (strongly or weakly)?
C. Does the mineral sample display a reaction with

acid (dilute HCl)?
D. If crystals are visible, then what is their crystal

form?
Introduction
E. Does the mineral sample have striations on

You are expected to learn how to identify common cleavage surfaces or crystal faces or exsolution
minerals on the basis of their properties and assess how lamellae ( FIGURE 3.15 )?

you depend on them. The ability to identify minerals is F. Estimate specific gravity (SG) as low,
one of the most fundamental skills of an Earth scientist. intermediate, or high.
It also is fundamental to identifying rocks, for you must

first identify the minerals comprising them. Only after G. Does the mineral sample have any unique
minerals and rocks have been identified can their origin, diagnostic properties like smell when scratched or
classification, and alteration be adequately under- during acid test?
stood. Mineral identification is based on your ability to 7. Use mineral identification figures to identify the name

describe mineral properties using identification charts of the mineral .

( FIGURES 3.18 – 3.20 ) and a Mineral Database ( FIGURE A. If the mineral is opaque and metallic or

3.21 ). The database also lists the chemical composition submetallic, follow steps 1–5 in FIGURE 3.18 .

and some common uses for each mineral. Some miner-

als, like halite (table salt) and gemstones are used in their B. If the mineral is light colored and nonmetallic,

natural state. Others are valuable as ores —materials from then follow steps 1–4 in FIGURE 3.19 .

which specific chemical elements (usually metals) can be C. If the mineral is dark colored and nonmetallic,
extracted at a profit. then follow steps 1–4 in FIGURE 3.20 .

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