Mineral Properties and Rock Classification

Physical and Chemical Properties of Minerals

• Minerals are identified through their physical and chemical properties, crucial for understanding rock formation.
• Common physical properties include color, luster, streak, hardness, cleavage, and fracture.
• Color: The visible hue of a mineral, though not always reliable for identification.
• Luster: Describes how a mineral reflects light; types include metallic and non-metallic.
• Streak: The color of the mineral in powdered form; tested by rubbing on a porcelain plate.
• Hardness: Measured by Mohs scale, which rates from 1 (talc) to 10 (diamond); a critical property for identification.
• Cleavage: The tendency of a mineral to break along flat surfaces; distinct patterns can indicate specific minerals.
• Fracture: Describes how a mineral breaks irregularly when it does not cleave.

Classification of Rocks

• Rocks are classified into three major types: igneous, sedimentary, and metamorphic, based on their formation process.
• Igneous Rocks: Formed from cooled and solidified magma or lava; examples include basalt and granite.
• Sedimentary Rocks: Created from the accumulation of sediments; often contain fossils and are formed through processes like compression and cementation; examples include sandstone and limestone.
• Metamorphic Rocks: Altered by heat, pressure, or chemically active fluids; can form from igneous, sedimentary, or other metamorphic rocks; examples include schist and marble.
• Understanding these classifications aids in recognizing the geological processes that shaped the Earth’s crust.

Physical and Chemical Properties of Minerals

• Minerals are identified through their physical and chemical properties, crucial for understanding rock formation.
• Common physical properties include color, luster, streak, hardness, cleavage, and fracture.
• Color: The visible hue of a mineral, though not always reliable for identification.
• Luster: Describes how a mineral reflects light; types include metallic and non-metallic.
• Streak: The color of the mineral in powdered form; tested by rubbing on a porcelain plate.
• Hardness: Measured by Mohs scale, which rates from 1 (talc) to 10 (diamond); a critical property for identification.
• Cleavage: The tendency of a mineral to break along flat surfaces; distinct patterns can indicate specific minerals.
• Fracture: Describes how a mineral breaks irregularly when it does not cleave.

Classification of Rocks

• Rocks are classified into three major types: igneous, sedimentary, and metamorphic, based on their formation process.
• Igneous Rocks: Formed from cooled and solidified magma or lava; examples include basalt and granite.
• Sedimentary Rocks: Created from the accumulation of sediments; often contain fossils and are formed through processes like compression and cementation; examples include sandstone and limestone.
• Metamorphic Rocks: Altered by heat, pressure, or chemically active fluids; can form from igneous, sedimentary, or other metamorphic rocks; examples include schist and marble.
• Understanding these classifications aids in recognizing the geological processes that shaped the Earth’s crust.