Resource Processing Quick Check
2 of 42 of 4 Items
Question
What is true about most higher-grade metallic ores?(1 point)
Responses
They are usually found deep below Earth’s surface—more than 1,000 ft underground.
They are usually found deep below Earth’s surface—more than 1,000 ft underground.
They are usually found very close to Earth’s surface—less than 1,000 ft underground.
They are usually found very close to Earth’s surface—less than 1,000 ft underground.
Most of them can be extracted without requiring drilling.
Most of them can be extracted without requiring drilling.
Most of them can be extracted using the placer method.
Most of them can be extracted using the placer method.
The correct answer is:
They are usually found very close to Earth’s surface—less than 1,000 ft underground.
The correct answer is: They are usually found very close to Earth's surface—less than 1,000 ft underground.
To determine which answer choice is true about most higher-grade metallic ores, we need to understand the nature of these ores and their typical locations.
Higher-grade metallic ores refer to ores that contain a high concentration of valuable metals, such as gold or copper. These ores are usually formed through geological processes over long periods of time. To find these ores, geologists and mining engineers conduct exploration and prospecting activities.
Answer Choice 1: "They are usually found deep below Earth’s surface—more than 1,000 ft underground."
This answer suggests that higher-grade metallic ores are usually found at significant depths, more than 1,000 ft underground. This is a commonly known characteristic of metallic ores, as they are often formed deep within the Earth's crust. This answer is correct.
Answer Choice 2: "They are usually found very close to Earth’s surface—less than 1,000 ft underground."
This answer suggests that higher-grade metallic ores are found close to the Earth's surface, less than 1,000 ft underground. However, this contradicts our understanding that these ores are usually found at greater depths. Therefore, this answer is not true.
Answer Choice 3: "Most of them can be extracted without requiring drilling."
This answer suggests that most higher-grade metallic ores can be extracted without drilling activities. While some surface deposits can be accessed without drilling, the majority of higher-grade metallic ores require drilling and excavation techniques to reach them. Therefore, this answer is not true.
Answer Choice 4: "Most of them can be extracted using the placer method."
The placer method refers to a mining technique that involves the separation of valuable minerals from the sediment or soil through a process called placer mining. This method is commonly used for extracting gold, but it is not generally applicable to most higher-grade metallic ores. These ores often require more complex mining processes, including underground mining or open-pit mining. Therefore, this answer is not true.
In conclusion, the true statement about most higher-grade metallic ores is that they are usually found deep below Earth's surface, more than 1,000 ft underground. The correct answer to the question is the first option: "They are usually found deep below Earth’s surface—more than 1,000 ft underground."