MineralsQ&A
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Barstow Community College *
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Geology
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Apr 30, 2024
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Minerals PowerPoint: Questions
Name: Roderick Taylor Directions:
Answer the following questions based on the Minerals PowerPoint. Be sure to place your answers underneath the questions and then either highlight, color or underline your answers. 1. What is the difference between a mineral and a rock?
Minerals are the building blocks of rocks. Minerals are naturally occurring, have a crystal structure, have a definite chemical composition, and are non-organic. Minerals combine together to form rocks.
2. Why isn’t cubic zirconia considered a mineral?
Cubic zirconia is manufactured and not naturally occurring. 3. Glass can’t be x-rayed because the silicon and oxygen atoms don’t line up in regular arrays. So what is glass lacking to be considered a mineral?
Glass is not a crystal structure because the atoms do not line up in a repeating array.
4. The mineral calcite is mostly made of calcium carbonate but some of the calcium can be replaced by magnesium. Which of the four parts of the definition of a mineral does this fall under?
A definite chemical composition
5. Why isn’t jet which is a very hard coal made into jewelry considered a mineral?
Minerals are non-organic and jet is produced from living things.
6. What classification do most minerals fall under?
Most minerals are silicates.
7. What geometric shape do silicates have with the silicon bonded to four oxygen? Silicates have one silicon atom bonded in a tetrahedron to 4 oxygen atoms.
8. Looking to the diagram on the far right, what silicate structure do mica and clays have? Mica and clays have a sheet silicate structure.
9. Looking at the non-silicates at the bottom left, which group does pyrite belong to?
Pyrite is in the sulfide group.
10. When panning for gold, the gold stays in the bottom of the pan and all the lighter minerals are floated out. What property of gold is being used here?
Density – Gold is heavier than the lighter minerals
11. If you hit a large block of salt coming out of a mine, it breaks into smaller and smaller cubes. What property of minerals is this called?
Cleave vs fracture – The salt breaks in directions that follow the cubic form
12. Geologists can often tell minerals apart by seeing which mineral can scratch another. What property of minerals is this called?
Hardness – The harder mineral will scratch the softer one.
13. In most mine dumps, you can see a bright gold mineral that is fool’s gold. It looks almost identical to real gold. What property of minerals is this called?
Color – Certain minerals are usually a certain color
14. Why is gold usually found by itself in nature as a pure element and not in a compound?
Gold is chemically very unreactive.
15. What property of gold discourages using pure 24kt gold in jewelry?
Hardness - gold is soft.
16. Gold is sometimes used to cover domes on ceremonial buildings. What property of gold allows this to be economically possible?
As far as hardness goes, gold is soft and can be rolled out into thin sheets that would allow covering the dome on a ceremonial building using a relatively small amount of gold.
17. Gold miners often look for where stream gravels meet depressions in the bedrock on river bottoms to find gold. What property of gold lets it accumulate in these depressions?
Density – gold is extremely heavy and sinks to the bottom of riverbeds. It is transported by only the most
violent storms.
18. What would gold mining companies have to do to the Sierra Nevada today to make large scale gold mining profitable? (Hint: the local residents and environmentalists would never let them do it)
They would have to blow up entire mountains and then run them through a mill.
19. What new piece of equipment that anyone can buy for a few hundred dollars is being used to find gold in the old mining tunnels? People are using metal detectors to find gold in old mining tunnels.
20. Placer mining is locating gold in streams and rivers. What is gold mining that uses tunnels into hard rock called? L____________ mining
Lode mining
21. What mineral is gold most commonly associated with?
Gold is commonly found in quartz veins.
22. What is the simple reason that placer mining has declined so much in California? Most of the easy to find gold has already been removed.
23. What is the best place for placer mining in southern California?
The best place for placer mining in southern California is the East Fork of the San Gabriel river above Azusa.
24. What type of large scale gold mining is profitable today? o__________ p________ mining
Open pit mining
25. What dangerous chemical is used to leach gold out of rocks?
The rock is leached with cyanide to extract the gold.
26. How many sides does a quartz crystal have?
Quartz crystals have six sides (hexagon).
27. What color is pure quartz with no metallic or water impurities?
Pure quartz is clear.
28. What is the most common mineral on Earth?
Feldspar is the most common mineral on Earth.
29. What does quartz need to grow into large hexagonal crystals?
Crystals need space to grow.
30. Why does quartz just form irregular grains in granite rock and not beautiful hexagonal crystals?
When magma is cooling, quartz is the last mineral to precipitate and has to squeeze into the irregular spaces between the earlier formed minerals.
31. Where does all the quartz that comes out of granite and gets carried down from the mountains by streams to rivers eventually end up? Hint: it is located in the highest real estate areas but you can visit it
for the day
The quartz released as sand-sized particles may eventually reach the beach to form beach sand.
32. Why does quartz last practically forever?
Quartz is so chemically tough that is practically lasts forever.
33. Why does gold remain in the super hot solutions moving through the crust until the very last minute
when everything cools down and it ends up in quartz? Gold doesn’t easily combine with other metals so it stays in the liquid base until it finally cools and quartz is the last mineral to precipitate. As a result, gold is often found with quartz.
34. Our mountains have very little gold compared to the northern Sierra Nevada. What seafloor feature
do our local mountains lack that the Sierra has? (just 2 words for the answer)
Hydrothermal vents
35. What causes amethyst to be purple colored?
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Natural irradiation of trace amounts of iron causes amethyst to be purple.
36. Why is almost all quartz milky white?
Most quartz contains microscopic water in the mineral causing the milky white color.
37. What type of silicate is tourmaline?
Tourmaline is a cyclo-silicate that contains boron.
38. Look at tourmaline’s chemical formula. What causes tourmaline to change color within one crystal and also to form in almost every color imaginable? Tourmaline has a very complicated formula and changes in the formula through the length of the mineral cause changes in the color.
39. What is the name of the flaking mineral at the base of the tourmaline columns?
Muscovite mica is a tannish sheet mineral at the base of tourmaline columns.
40. Where is the tourmaline mining district located in SoCal?
The tourmaline mines in southern California are located in Riverside and San Diego counties.
41. Most tourmaline is not a gemstone. What is the name for common tourmaline (98%)?
Common tourmaline is schorl.
42. Which is your favorite tourmaline gemstone on slide #15?
The colorful rubellite is my favorite.
43. What are 2 utilities supplied to all the tourmaline mines? The mines have ventilation tubing to bring in fresh air and an electrical line from a generator to power lights and electric drills.
44. What are the people doing in slide #16?
They are going through a dig pile to find tourmaline.
45. What soft mineral in the gem pockets do the tourmaline minerals grow into?
The tourmaline minerals grow into pockets of clay.
46. What are large minerals that grew from magma solutions called? Pegmatites are large minerals that grow from magma solutions.
47. What is the last mineral that precipitates out of magma solutions? Hint: it’s the second most common mineral on Earth
Quartz is the last mineral to precipitate out of magma solutions.
48. What lithium bearing mineral is commonly found with tourmaline?
Lepidolite contains lithium and is commonly found with tourmaline.
49. If you wanted to get into the gem trade, where could you attend classes in SoCal?
The Geological Institute of America in Carlsbad, California.
50. If you didn’t have the money for tuition at GIA, how else could you learn the gem trade or mining?
You can apprentice with someone already in the gem trade by working at a minerals shop or a gem mine.
51. What type of mine is Rio Tinto’s boron operation in the Mojave?
It is an open pit mining operation.
52. Technically, which term refers to the mineral? borate or boron
Borate refers to over 100 borate minerals.
53. In what environment did these borate minerals form?
Borate minerals form lake waters in arid environments as the waters repeatedly evaporate and concentrate the element.
54. What does the mineral ulexite do to printed letters? It magnifies the printed letters.
55. Which of the 4 borate minerals is named for the county where the mine is located?
Kernite is named after Kern county.
56. What product do you have in your house that might have boron in it?
The laundry detergent I use may have boron in it.
57. What valuable element is Rio Tinto planning to extract from its waste piles?
Rio Tinto is going to extract lithium from their waste piles.
58. What element did Rio Tinto initially hope to recover from their 100 years of accumulated waste piles? Rio Tinto was originally going to extract gold from their waste piles.