Question

Which of the following is a common rockforming mineral? A. azurite C. quartz B. gold D. diamond

Short answer

Quartz

Step-by-step solution

Understanding the Question

The question asks for a common rock-forming mineral among the given options. Rock-forming minerals are minerals that make up the majority of Earth's crust.

Analyzing the Options

Let's analyze the given options: azurite, quartz, gold, and diamond, and determine which one is known as a common rock-forming mineral.

Identifying Rock-Forming Minerals

Rock-forming minerals are typically silicate minerals like quartz, feldspars, and micas. Let's check each option to see which fits this category: - Azurite is a copper carbonate mineral, not commonly found in large quantities in rocks. - Quartz is a silicate mineral and one of the most abundant rock-forming minerals. - Gold is a native metal, not a common component of most rocks. - Diamond is a carbon structure, rare and not considered a rock-forming mineral.

Selecting the Correct Answer

Based on our analysis, quartz (option C) is the only mineral from the options that is categorized as a common rock-forming mineral because it is prevalent in the Earth's crust.

Key concepts

Quartz

Quartz is one of the most abundant and significant rock-forming minerals in the Earth's crust. It is a member of the silicate minerals, which make up about 90% of the Earth's crust. Quartz is primarily composed of silicon dioxide (SiO₂). Its crystal structure consists of silicon atoms surrounded by oxygen atoms in a continuous framework. This structure gives quartz its hardness and durability.
Quartz is found in a variety of geological environments and is a major component of many igneous, metamorphic, and sedimentary rocks. Here are some key features of quartz:

• Hardness: Quartz is relatively hard, rating a 7 on the Mohs scale of mineral hardness.
• Color: It exhibits a wide range of colors, including clear, white, pink, and purple, depending on impurities and other mineral inclusions.
• Uses: Quartz is not only abundant but also commercially important. It is used in glassmaking, ceramics, and as a component in electronic devices.

The presence of quartz is crucial in identifying rock types and understanding geological histories.

Silicate Minerals

Silicate minerals form the largest and most important class of minerals, constituting approximately 90% of the Earth's crust. These minerals are characterized by their silicate based chemical structure, particularly the silicon-oxygen tetrahedron (SiO₄)⁻⁴. This structure forms the basis for many different silicate minerals, each with its own distinct properties.
Some common silicate minerals include:

• Quartz: As mentioned earlier, it's a simple silicate mineral composed solely of silicon and oxygen.
• Feldspars: These are the most abundant minerals in the Earth's crust and come in two main types, plagioclase and alkali feldspar.
• Micas: Featuring a sheet-like structure, these minerals, like biotite and muscovite, are easily split into thin, flexible sheets.

Silicate minerals are essential for understanding geology as they influence the physical properties of rocks, such as their hardness, color, and density. The variety of silicate structures also provides insights into the temperature and pressure conditions of the rocks' formation.

Earth's Crust

The Earth's crust is the outermost layer of our planet and is composed primarily of rock-forming minerals. It is relatively thin compared to other layers, such as the mantle, but is crucial for supporting life and forming the planet's surface. The crust is primarily made up of silicate minerals, which account for its structure and composition.
The Earth's crust can be categorized into two main types:

• Continental Crust: This thicker part of the crust is composed of rocks such as granite that are rich in silicates like quartz and feldspar.
• Oceanic Crust: Thinner and denser than the continental crust, it primarily consists of basaltic rocks, which contain minerals like pyroxene and olivine.

Understanding the composition of the Earth's crust is essential for geologists as it aids in studying plate tectonics, volcanic activity, and seismic events. The abundance of silicate minerals within the crust highlights their importance in Earth's geological processes and history.