Homework: Chapter 12

Heap-leach extraction involves piling crushed ore into large piles and spraying it with ________________.

an alkaline-cyanide solution

Starting at the Earth’s surface and going towards the center of the Earth, what is the correct order of Earth’s layers that make up the Mantle?

crust, uppermost mantle, asthenosphere

__________ rocks are often the source of metal ores such as gold, silver, and copper.

Metamorphic

Half the coal used in the United States comes from this extraction process:

strip mining

Building and farming on a flood plain decreases the land's ability to absorb flood waters.

True

The continental crust of the earth is _____________ while the oceanic crust is _____________.

thicker and lighter than the oceanic crust; similar in composition to the mantle

The eruption of a volcano can cause global climate changes by causing stratospheric ozone reduction, allowing increased ultraviolet light to reach the Earth's surface.

False

If metals are deposited in stream-beds _____ would probably be used.

placer mining

Evaporites, formed from ___________, are important economically because they are often found at or above 97% purity and are __________.

evaporation of mineral solutions such as salt water; therefore concentrated in economically recoverable levels

Which is not a major category of economic minerals?

• bauxite

• metal ores

• sand and gravel

• evaporated salt flats

• None of these are correct.

None of these are correct.

Why is recycling metals an economic benefit as well as a tool for conservation of resources?

It takes much less energy to produce metal products from scrap than to mine new metal ore.

Metamorphic rocks are produced when rocks are

formed by heat and pressure.

Which resource has the highest recycling rate?

steel

________ in the mantle and core make tectonic plates move.

Convection currents

"Subduction" is the process of a tectonic plate

being forced below another late.

Problems associated with gemstones and precious metals such as gold and diamonds would not be attributed to which of the following?

Their distribution to developed nations is often banned.

Rocks are _______ in the process called the rock cycle.

broken down and converted to new types of rock

Use the following scenario in answering the question. After reading a newspaper article about gold mining prospects near your home town, your sister commented that it seems as though miners are going after ores with less and less concentrations of the gold. She mentions the rich gold veins and nuggets that she reads about in historical accounts of gold mining and wonders what factors have lead to the change. She tells you that she knows that the days of gold nuggets in the streams are gone, but that she can't believe how small the percentage of gold is in the ore they are now mining. First, you tell your sister that she sounds like your father, commenting on the good old days. Then you explain to her that there are many factors driving the changes and that there are important environmental implications of the mining.

Which of the following factors were not in your explanation?

As supplies decrease and prices rise it is less rewarding to explore for new sources of the gold.

Use the following scenario in answering the question. After reading a newspaper article about gold mining prospects near your home town, your sister commented that it seems as though miners are going after ores with less and less concentrations of the gold. She mentions the rich gold veins and nuggets that she reads about in historical accounts of gold mining and wonders what factors have lead to the change. She tells you that she knows that the days of gold nuggets in the streams are gone, but that she can't believe how small the percentage of gold is in the ore they are now mining. First, you tell your sister that she sounds like your father, commenting on the good old days. Then you explain to her that there are many factors driving the changes and that there are important environmental implications of the mining.

A major environmental implication of the quest for more gold at lower concentrations in the ore compared to higher concentrations is that

more material has to be moved to get to the gold.

A giant sea swell known as a tsunami is caused by

earthquakes.

Rock formed from magma extruded to the surface through volcanic vents is classified as

igneous.

Nuees ardentes are sonic waves associated with earthquakes.

False

The need for extraction of raw metals for making steel has been reduced due to the

increase in minimills.

What gas is released in the process of smelting?

sulfur dioxide

The United States keeps large stockpiles of bauxite to ensure a supply of aluminum. This is an example of

a strategic metal.

Which environmental impact would not be a result of placer mining?

contamination of underground aquifers

Why would the environmental degradation associated with mining be a low priority for a less-developed country?

The country relies on the export of a mineral for the majority of their foreign exchange.

Pressurized fluid injected into a well is used in a mining process called

fracking.

Smelting releases metals from ore.

True

Which of the following is NOT a result of mountaintop removal mining?

It has increased the amount of cleared land available for development after the mine closes.