Question

Consider the following statements about Amphibole: Which of the statements above are correct?

1. It makes up 7% of the Earth's crust.
2. Its chemical composition lacks Aluminum.
3. It is a primary source for making asbestos.

• A. None of these
• B. 3 only
• C. All
• D. 1, 3

Answer 1

Answer:

D. 1, 3

• Amphibole group minerals are a complex series of double-chain silicates.
• They constitute approximately 7% of the Earth's crust, making them a significant component of igneous and metamorphic rocks. This abundance is a key factor in geological studies and resource exploration.
• A defining characteristic of many amphiboles is the presence of Aluminum (Al) in their chemical formula, often substituting for silicon (Si) and other cations like iron (Fe) and magnesium (Mg). Therefore, the statement that its chemical composition lacks Aluminum is incorrect.
• Certain amphiboles, particularly those in the tremolite-actinolite series, are known to form fibrous crystals that are classified as asbestos. These types of amphiboles have been historically mined as a primary source for asbestos production due to their valuable properties like heat resistance and insulation. However, due to health risks associated with asbestos exposure, its use is now highly regulated or banned in many countries.
• The presence and types of amphiboles in rocks are crucial indicators for geologists in determining the conditions (temperature, pressure, and chemical environment) under which these rocks formed.