WEEK 8 - Metals Flashcards
1
Q
What are Native Metals?
A
Metals found in their pure, elemental form in nature
2
Q
Native Metals Historical Value
A
Their value in ancient times was partly due to their rarity
3
Q
Examples of Native Metals
A
- Native Copper
- Native Gold
- Native Silver
4
Q
What are metal compounds?
A
- Metal compounds are minerals where metals are combined with other elements like sulphur or oxygen.
Examples:
- Galena – lead sulphide
- Sphalerite – zinc sulphide
- Magnetite – iron oxide
5
Q
Why were metal compounds important historically?
A
- The increased use of metals led to the development of smelting techniques to extract metals from these impure compounds.
- Smelting separated the metal from the sulphur or oxygen in the compounds, making metals like lead, zinc, and iron more accessible for use in tools, construction, and industry.
6
Q
What are the general properties of metals?
A
- High electrical conductivity
- Luster (shiny appearance)
- Malleability (can be shaped without breaking)
- Ability to lose electrons and form positive ions (cations)
7
Q
What are “fusible metals”?
A
- Metals of moderate hardness.
- They can be melted and combined with other metals to form alloys (mixtures of metals).
8
Q
How are fusible metals classified?
A
- Precious metals
- Base metals
9
Q
What are precious metals?
A
- Precious metals are metals that are rare and have high value (e.g., gold, silver, platinum).
- Often used for jewelry or coins
- They are desirable for electrical components due to their resistance to corrosion and oxidation.
10
Q
What are base metals?
A
- Base metals are more common metals, often used in industry (e.g.,Iron, Lead, Copper, Zinc, Inc)
- Have low intrinsic value compared to precious metals.
- Most base metals oxidize (tarnish) in air.
- The term comes from the practice of alchemists trying to make gold from less valuable metals.
11
Q
What makes up most of Earth’s crust?
A
98.5% of Earth’s crust (by weight) is made up of 8 elements:
- Oxygen (O) - 46.6%
- Silicon (Si) - 27.7%
- Aluminum (Al) - 8.1%
- Iron (Fe) - 5.0%
- Calcium (Ca) - 3.6%
- Sodium (Na) - 2.8%
- Potassium (K) - 2.6%
- Magnesium (Mg) - 2.1%
12
Q
Other element’s in earth’s crust?
A
- 1.5% of Earth’s crust is made up of all other elements
- Most metals used in society (besides iron and aluminum) don’t appear on the list of the 8 most abundant elements.
13
Q
What is the abundance of base metals in the earth’s crust?
A
Base metals (other than iron, aluminum, and titanium) in the continental crust:
- Copper: 0.0055%
- Nickel: 0.0075%
- Zinc: 0.0070%
- Lead: 0.00125%
- Tin: 0.00020%
14
Q
What is the abundance of precious metals in the earth’s crust?
A
Precious metals in the continental crust:
- Silver: 0.000007%
- Gold: 0.0000004%
- Platinum: 0.0000005%
15
Q
What does “Enrichment” of metals mean?
A
- Metals don’t occur in uniform abundance throughout the Earth’s crust.
- Certain geological circumstances cause metals to occur in higher concentrations (enrichment).
16
Q
Why is understanding enrichment important for Geologists?
A
- Geologists study the processes and environments that lead to metal enrichment.
- This knowledge helps discover metal-rich deposits, which is essential for metal mining and use.
17
Q
How does geology impact daily life?
A
Geologists help find valuable metal deposits, influencing the availability of materials used in technology, infrastructure, and more.
18
Q
What is magmatic cooling in the context of metal enrichment?
A
- Some metals, like iron and chromium, can be concentrated by the cooling of magma.
- Heavy minerals like magnetite (Fe3O4) and chromite (FeCr2O4) form during cooling and sink to the bottom of the magma chamber.
19
Q
How does gravitational settling contribute to metal enrichment?
A
- Heavy minerals (like magnetite and chromite) sink to the bottom of the magma chamber due to gravity during cooling.
- This results in layers with high concentrations of these metals.
20
Q
What do the dark and light bands in magma cooling represent?
A
- Dark bands: Concentrated heavy minerals like magnetite, chromite, and platinum.
- Light bands: Silicates, which are lighter minerals.
21
Q
What are the igneous processes that lead to metal enrichment?
A
- Magmatic Cooling
- Immiscibility
- Hydrothermal Processes
22
Q
What is immiscibility in the context of metal enrichment?
A
- Immiscibility refers to the separation of metal-rich liquid from silicate-rich liquid.
- It occurs when a metal-rich liquid (like nickel) separates from a silicate liquid, similar to how oil separates from water.
23
Q
What role did the Sudbury structure play in metal enrichment?
A
- The Sudbury structure is believed to be a meteorite impact crater, which was later compressed into an oval shape by tectonic forces.
- The impact event caused heat that melted rock far below the surface, allowing metal-rich liquid to separate from the silicate liquid.
24
Q
How did the Sudbury Basin form?
A
- After the meteorite impact, molten material rose to the surface.
- Metal-rich liquid separated from silicate liquid and was concentrated in cracks around the impact crater.
- The crater basin was later filled with sediment.
25
What does nickel ore from Sudbury look like?
- Nickel occurs in rounded bodies of bronze-colored pentlandite (Fe, Ni)9S8, which crystallized from immiscible fluids.
- Dark-colored mafic silicate minerals surround the pentlandite bodies.
- The ore also contains copper (in chalcopyrite) and platinum.
26
What are hydrothermal processes?
- Formation of ore deposits from hot-water solutions.
Can come from:
- Can come from:
- Left-over fluids from cooled magma
- Groundwater or seawater seeping into rocks below the surface.
27
What factors affect the ability of water to dissolve metals?
- "Saltiness" of the water: brine solutions (salty water) dissolve metals better than pure water.
- Higher temperature increases the amount of metals water can hold in solution.
28
How do metal deposits form in hydrothermal processes?
- Hot brine with dissolved metals cools down.
- Metals are deposited as the water cools, forming metallic mineral deposits.
29
How do hydrothermal processes occur at convergent boundaries?
- Magma formed at convergent boundaries is intermediate to felsic in composition.
- Limited fluid remains in the magma chamber after most silica has crystallized.
- This fluid is very salty and concentrated in heavy metal ions.
30
What happens to the salty fluid in the magma chamber at convergent boundaries?
- The fluid can penetrate cracks around igneous intrusions.
- Once cooled, metals are dropped out of solution.
- Metals form mineral compounds or native metals.
31
What are disseminated deposits?
- Formed when pressure from an igneous body creates microscopic cracks in surrounding rock.
- Residual fluid can penetrate these cracks and cool, forming mineral deposits.
32
Which minerals are found in disseminated deposits?
- Copper, molybdenum, gold, and silver.
- These minerals are spread throughout the fractured rock in low concentrations (disseminated).
33
Are disseminated deposits valuable?
- Though low in grade (concentration), they are very large in scale.
- Can be mined at a profit despite the low concentration.
34
What are vein (lode) deposits?
- Formed when super-concentrated fluids in metals penetrate larger fractures.
- These fluids fill fractures, forming mineral-filled veins.
35
What minerals are found in vein deposits?
Native gold and silver can be found in the spaces between quartz crystals.
36
What is the "Mother Lode"?
- The "Mother Lode" refers to a belt of quartz veins in California.
- It was the source of the famous gold during the California gold rush of the 1800s.
37
What are gold-bearing quartz veins?
- Gold can be found in quartz veins in deposits like Timmins, Ontario.
- These veins are formed when mineral-rich fluids deposit gold within quartz fractures.
38
What is "leaf silver"?
- Leaf silver is found in vein deposits like those in Cobalt, Ontario.
- It refers to silver that appears in thin, flat sheets.
39
What are pegmatites?
- Pegmatites are a type of rock formed from late crystallization of magma.
- Typically felsic (similar to granite) with large crystals.
40
What metals and gems are commonly found in pegmatites?
- Pegmatites contain high concentrations of rare metals like beryllium, lithium, and tantalum.
- They can also contain gemstones like emeralds.
