Minerals II: Properties and Identification

In this study guide, we will explore the properties of minerals and methods for their identification.

Properties of Minerals

Minerals have specific properties that can be used to identify and distinguish them from each other. These properties include:

• Color: The color of a mineral can vary, but it is not a reliable indicator for identification, as many minerals can occur in different colors.
• Luster: This refers to the way light is reflected from the surface of a mineral. Common types of luster include metallic, vitreous (glassy), and dull.
• Hardness: The resistance of a mineral to scratching. The Mohs scale is used to measure hardness, with talc being the softest (rated 1) and diamond being the hardest (rated 10).
• Cleavage and Fracture: Cleavage refers to the way a mineral breaks along flat planes, while fracture refers to the way it breaks irregularly.
• Crystal Form: Some minerals have distinctive crystal shapes, which can aid in their identification.
• Specific Gravity: The ratio of the weight of a mineral to the weight of an equal volume of water. This property can help distinguish between minerals with similar appearances.

Identification of Minerals

There are several methods for identifying minerals:

1. Observation: Careful observation of a mineral's properties, including color, luster, hardness, cleavage, fracture, and crystal form.
2. Streak Test: Rubbing a mineral against an unglazed porcelain tile to determine its streak color, which may differ from its outward color.
3. Acid Test: Reacting a mineral with hydrochloric acid to observe the resulting effervescence, which can indicate the presence of carbonate minerals such as calcite.
4. Magnetism: Testing whether a mineral is attracted to a magnet, which can help identify magnetic minerals such as magnetite.
5. Specific Gravity Test: Measuring the specific gravity of a mineral using a balance and comparing it to known values for different minerals.

Study Tips

When studying minerals, it can be helpful to:

• Use flashcards to memorize the properties of different minerals.
• Practice identifying minerals using mineral samples or pictures of minerals.
• Review the Mohs scale of hardness and its corresponding minerals.
• Take note of any distinctive features or characteristics of specific minerals to aid in their identification.

By understanding the properties of minerals and utilizing identification methods, you can develop the skills needed to identify and appreciate the diversity of minerals found in the Earth's crust.