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Minerals.

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Presentation on theme: "Minerals."— Presentation transcript:

1 Minerals

2 1) Specific Gravity Today
Mineral Properties The following are a list of physical properties that minerals could display: 1) Specific Gravity Today 2) Hardness 3) Cleavage Versus Fracture 4) Streak 5) Luster 6) Colour 7) Others Taste, Feel, Magnetism, Acid Test, Crystal Form, Smell, Double Refraction, Tenacity, and Fluorescence.

3 Specific Gravity Specific Gravity (SG): is the mass of a mineral compared to that of an equal volume of water. To determine specific gravity, you need to carry out the following three steps: Weigh the specimen in air and record the weight. 1)

4 Specific Gravity 2) Weigh the specimen submerged in water and record the weight.

5 Specific Gravity Calculate specific gravity (SG) using the following formula: 3) Specific Gravity = weight in air weight in air - weight in water Note that if a cubic centimeter of a mineral weighs three times as much as a cubic centimeter of water, then its specific gravity is 3. With a little practice, you can estimate the SG of minerals by “hefting” them in your hand.

6 Specific Gravity = Density
Note: (In Reference to Core Lab #3) Because pure water at 4ºC has a density of 1 g/cm3, the specific gravity is equal to its density. Thus, Specific gravity = Density. Specific gravity has no units (it is simply a number), whereas density has units (i.e. g/cm3). To determine density you need to: 1) Use a scale to measure the mass of the mineral sample. 2) Find the volume of the mineral sample. 3) Calculate density (which equals specific gravity). Density = Mass(mineral) Volume(mineral) = Specific Gravity

7 Specific Gravity Given: 1mL = 1cm3 = 1g, we know the weight of an equal volume of water in grams. We can then use the following formula to calculate specific gravity: Calculation S.G. = W(mineral) W(water)

8 Specific Gravity Given: 1mL = 1cm3 = 1g, we know the weight of an equal volume of water in grams. We can then use the following formula to calculate specific gravity: Calculation S.G. = W(mineral) W(water) S.G. = = S.G. = =

9 Sample Problem Explain how the specific gravity of a mineral is determined. Answer: Specific gravity compares the weight of a mineral to the weight of an equal volume of H2O. Find the mass of the mineral; using a scale or balance. Find the volume of the mineral; using the water displacement method. Find the weight of the mineral in water; by suspending the mineral from the spring scale and weighing it immersed in water. Use the formula; S.G. = density = m/v OR S.G. = (weight of mineral in air) (weight in air) - (weight in H2O)

10 Will be completing two Assignments and a lab on this topic


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