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Minerals and Rocks. Chapter 3. What is a Mineral ?. Figure 3.5c. A mineral is a naturally occurring crystalline solid, inorganic, with definite chemical composition and distinct properties. Importance of Minerals. Figure 3.2. All matter, including minerals and rocks, made of atoms
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Minerals and Rocks Chapter 3
What is a Mineral? Figure 3.5c A mineral is a naturally occurring crystalline solid, inorganic, with definite chemical composition and distinct properties
Figure 3.2 • All matter, including minerals and rocks, made of atoms • Atom structure: Nucleus (proton and neutron) and surrounding electrons • Atomic number: The unique number of protons in an element’s nucleus • Atomic mass number: The sum of the number of protons and neutrons
Why do rocks melt? • 1. Geothermal gradient: temperature increases within the earth • 2. Decompression melting: as warm solid material rises the volume of overlying rock decrases • 3 Addition of water to magmas lowers melting temperature
Sedimentary Rocks • Formed at the surface environment conditions • About 75% of all rocks exposed at the surface are sedimentary • Reveal conditions on earth over time: fossils, climate, landscapes • Help Determine relative age
Metamorphic Rocks • Changed rocks from preexisting rocks under solid state: NO MELTING! • Changes in mineralogy and rock textures but little change in overall composition • Agents of change: Temp, pressure, and chemically active fluid • EVIDENCE of Earth’s dynamic processes: Tectonic movement and igneous intrusion
Figure 3.28b Failure of St. Francis Dam in California