Question

ntatinn of ave Effervescence: A mineral may react (fizz) when a drop of weak hydrochloric acid is placed on its surface Habit: Characteristic form in which the mineral grows. Related to crystal structure. What would you use a streak plate for? How soft does a mineral have to be for you to scratch it with your fingernail? How hard does a mineral have to be for it to scratch a glass plate? Describe the difference between cleavage and fracture. Why is the color not always useful for identifying the mineral? 3 Take the following minerals from the box: Graphite 1. 5. Hematite Quartz (crystal) 7, 13. Calcite Using your fingernail, the penny and the glass plate, list these minerals in order of their hardness. Softest Hardest Describe in your own words how you made this determination. 4 Take the following minerals from the box: Quartz (milky) 8. Halite 11. Calcite 13. 14. Gypsum Sketch the shape of each sample, and show any cleavage planes that you can identify. C Which sample has fracture, but no cleavage planes? All of the other samples have the same number of cleavage planes - how many cleavage planes to they have? LC In which sample are the cleavage planes at right angles? The other 2 samples have very similar cleavage plane angles, but one effervesces when a drop of acid is placed on its surface. Which sample does this? Describe in your own words how you would identify each of these samples if you were given a group of unknown minerals that all had this similar clear/white color. 6 Take the following minerals from the box: Galena 2. Pyrite 4. Hematite 5. Microcline 15. What is the color, streak and luster of each of these minerals? 4. 5. 15. Take sample 15, and check its hardness using the glass plate. What does this tell you about the streak of this sample? In which samples are the color and streak the same? In which samples are the color and streak different? 7 Take a look at other samples of hematite from other sample boxes around the room. Do they all have the same color, luster and streak? Describe the variability. What is the one thing that is consistent among all of the hematite samples?

Answer 1

ntatinn of ave Effervescence: A mineral may react (fizz) when a drop of weak hydrochloric acid is placed on its surface. Calcite reacts with the HCl. Habit: Characteristic form in which the mineral grows. Related to crystal structure. What would you use a streak plate for? Streak plate used to know the colour of the mineral powder and hardness of mineral. How soft does a mineral have to be for you to scratch it with your fingernail? Finger nail hardenss is 2.5 How hard does a mineral have to be for it to scratch a glass plate? Glass plate hardness is 5.5 Describe the difference between cleavage and fracture. Cleavage is the surface along with the mineral breaks by giving smooth surface. Whereas freature surfaces are not smooth. Minerals which have less than 3sets of cleavage surfaces will have fracture plane. Why is the color not always useful for identifying the mineral? Because so many minerals show same type of colors. That's why along with color we have to examine the streak, sp.gravity, hardness etc. 3

Take the following minerals from the box: Graphite 1. 5. Hematite Quartz (crystal) 7, 13. Calcite Using your fingernail, the penny and the glass plate, list these minerals in order of their hardness. Graphite (1) Calcite (3) Hematite (6.5) Quartz (7) Softest Hardest Describe in your own words how you made this determination. Graphite can be sctretched by finger nail, wheraas all others are not. Caclite sctetch by coin. Hematite can scretch by steel nail. Quatrz can't be scretched by all above 3. 4