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Mineral Identification. Chapter 3 Section 3. Minerals can be identified by their physical characteristics. The physical properties of minerals are related to their chemical composition and bonding. (That’s why we reviewed bonding). Introduction.
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Mineral Identification Chapter 3 Section 3
Minerals can be identified by their physical characteristics. • The physical properties of minerals are related to their chemical composition and bonding. • (That’s why we reviewed bonding) Introduction
Mineralogists are scientists who study minerals. • One of the things mineralogists must do is identify and categorize minerals. • most are recognizable using physical properties. • Color • Streak • Luster • Specific gravity • Hardness • Cleavage • Fracture How are minerals identified
Color is rarely very useful for identifying a mineral. Different minerals may be the same color. • The same mineral may also be found in different colors. Gold and Pyrite Quartz Color, Streak, and Luster
Streak is the color of a mineral’s powder. • Streak is a more trustworthy property than color because streak does not vary. • Minerals that are the same color may have a different colored streak. • To check streak, scrape the mineral across an unglazed porcelain plate Color, Streak, and Luster
Luster describes the reflection of light off a mineral’s surface. • Luster can be classified as metallic and non-metallic. • Metallic minerals are opaque and shiny Color, Streak, and Luster
Nonmetallic minerals Color, Streak, and Luster
The specific gravity of a substance compares its density to that of water. • Density = mass/volume • Substances that are more dense have higher specific gravity. Specific Gravity
Hardness is a measure of whether a mineral will scratch or be scratched. Mohs Hardness Scale. • Mohs Hardness Scale: 1 (softest) to 10 (hardest). Hardness
Breaking a mineral breaks its chemical bonds. Since some bonds are weaker than other bonds, each type of mineral is likely to break where the bonds between the atoms are weaker.. • Cleavage is the tendency of a mineral to break along certain planes to make smooth surfaces. • Fracture is a break in a mineral that is not along a cleavage plane. Cleavage and Fracture
Fracture Cleavage Cleavage and Fracture