Table 3. Specific Gravity Mineral Letter Dry Mass (g) Total Volume (mL) Displace
ID: 112311 • Letter: T
Question
Table 3. Specific Gravity
Mineral Letter
Dry Mass (g)
Total Volume (mL)
Displaced Volume (mL)
Specific Gravity
A
B
C
D
E
F
G
H
I
Use Table 3 to answer the following question:
1. Which mineral had the highest specific gravity? What does this tell you about the elements (or compounds) that make up this mineral? (Hint: Think about how elements are arranged on the periodic table based on their properties.)
EXERCISE 1 POST-LAB QUESTIONS
1. Why is it helpful to measure the specific gravity of a mineral?
2. How would a mineral’s specific gravity be affected if the mineral contained impurities (other elements not normally part of a mineral’s atomic structure)?
EXERCISE 2 DATA SHEET
Table 5. Mineral Identification
Mineral Sample
Color/
Clarity
Luster
Streak
Hardness
Cleavage
Other Distinctive Properties
Name of Mineral
A
B
C
D
E
F
G
H
I
1. What properties of Mineral B could be used to distinguish it from gold?
Write the name of Mineral B, its common nickname (see Figure 4) and fill in the data about each of the properties. Compare the differences between the two minerals and summarize your findings in a short paragraph. Is the nickname accurate? Why or why not?
2. Marble is a rock that is composed primarily of the carbonate minerals calcite (CaCO3) and dolomite (Ca,Mg(CO3)2). In Exercise 2, you saw the way carbonate minerals react to a drop of acetic acid. Based on this observation, why do you think people who care for monuments and sculptures made of marble are concerned about acid rain?
1. Which of the following terms are useful for describing the luster of nonmetallic minerals? (Select all that apply.)
A. Vitreous
B. Translucent
C. Earthy
D. Shiny
E. Silky
Answer: A
2. True or False? A mineral with a lower Mohs Hardness number will scratch a mineral with a higher Mohs Hardness number.
Answer: False
3. __________ refers to the way the surface of a mineral reflects light.
Answer: luster
4. Describe why it is not a good idea to use only color and clarity to identify a mineral.
Mineral Letter
Dry Mass (g)
Total Volume (mL)
Displaced Volume (mL)
Specific Gravity
A
B
C
D
E
F
G
H
I
Explanation / Answer
1. Why is it helpful to measure the specific gravity of a mineral?
Specific gravity of a mineral is the quotient of its weight and the weight of an equivalent volume of water at 4 ° C (conditions of maximum water density), being a dimensionless value. On the contrary, the relative density is an equivalent value corresponding to mass per unit volume and is expressed in units such as g / cm3.
Specific gravity is an intrinsic and constant property for a mineral of particular chemical composition and depends basically on two factors:
Of the atoms that constitute the mineral.
Of the type of packing of atoms.
Knowing the specific gravity of a body can be very important at the industrial level to determine what are the best conditions for its processing, for example. Everything will depend on the characteristics of the product you are planning to obtain. Thanks to the determination of the specific weight, and also in some cases of density, the best physical and physiological quality of certain products can be obtained, such as rice, wine (through the analysis of the must, since the greater weight specific, higher sugar content), gems and cement.
2. How would a mineral’s specific gravity be affected if the mineral contained impurities (other elements not normally part of a mineral’s atomic structure)?
In the isostructural elements, with the same type of packing, the elements of greater atomic weight have higher relative density. In a series of solid solutions there is a continuous change in relative density. Thus, in the case of the series of the wolframites, the extreme terms ferberite (MnWO4) and hubnerite (FeWO4) have values respectively.
The opposite case consists of polymorphous compounds, of the same composition but different type of packaging. Thus, in the case of carbon, we went from values of 3,515 for diamond to only 2.23 for graphite despite having the same chemical formula.
Acid precipitation affects stone primarily in two ways: dissolution and alteration. When sulfurous, sulfuric, and nitric acids in polluted air react with the calcite in marble and limestone, the calcite dissolves. In exposed areas of buildings and statues, we see roughened surfaces, removal of material, and loss of carved details. Stone surface material may be lost all over or only in spots that are more reactive.
2. Marble is a rock that is composed primarily of the carbonate minerals calcite (CaCO3) and dolomite (Ca,Mg(CO3)2). In Exercise 2, you saw the way carbonate minerals react to a drop of acetic acid. Based on this observation, why do you think people who care for monuments and sculptures made of marble are concerned about acid rain?
1. Which of the following terms are useful for describing the luster of nonmetallic minerals? (Select all that apply.)
A. Vitreous
B. Translucent
C. Earthy
D. Shiny
E. Silky
2. True or False? A mineral with a lower Mohs Hardness number will scratch a mineral with a higher Mohs Hardness number.
Answer: False
"Hardness" is the resistance of a material to being scratched. The test is conducted by placing a sharp point of one specimen on an unmarked surface of another specimen and attempting to produce a scratch. Here are the four situations that you might observe when comparing the hardness of two specimens:
Luster should not be confused with color: A brass-yellow pyrite crystal has a metallic luster, but so does a shiny grey galena crystal . Quartz is said to have a glassy (or vitreous) luster, but its color may be purple, rose, yellow, or any of a wide range of hues. Tha is why the correct answer is A
You might expect that sheltered areas of stone buildings and monuments would not be affected by acid precipitation. However, sheltered areas on limestone and marble buildings and monuments show blackened crusts that have spalled (peeled) off in some places, revealing crumbling stone beneath. This black crust is primarily composed of gypsum, a mineral that forms from the reaction between calcite, water, and sulfuric acid. Gypsum is soluble in water; although it can form anywhere on carbonate stone surfaces that are exposed to sulfur dioxide gas (SO2), it is usually washed away. It remains only on protected surfaces that are not directly washed by the rain. Gypsum is white, but the crystals form networks that trap particles of dirt and pollutants, so the crust looks black. Eventually the black crusts blister and spall off, revealing crumbling stone.
3. __________ refers to the way the surface of a mineral reflects light.
Answer: luster
Luster refers to how light is reflected from the surface of a mineral. The two main types of luster are metallic and nonmetallic.
4. Describe why it is not a good idea to use only color and clarity to identify a mineral.
Amineral is identified by the following properties:
Luster
Color
Streak
Cleavage and fracture
Hardness
Density
Special Properties
is not a good idea to use only color and clarity to identify a mineral because weathering and impurities can change the color.
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