WHAT IS A MINERAL? - A NATURALLY OCCURRING SOLID THAT CAN FORM BY INORGANIC PROCESSES AND THAT HAS A CRYSTAL STRUCTURE AND A DEFINITE CHEMICAL COMPOSITION. - REQUIREMENTS: - 1. Naturally occurring: formed by natural processes - 2. Solid: have a definite volume and shape - 3. Crystal structure: particles line up in a repeating pattern (flat sides that meet a sharp edges and corners) - 4. Forms by Inorganic processes: must form from materials that were NOT living things - 5. Definite Chemical Composition: always contains certain elements in definite proportions Properties of Minerals

How Are Minerals Identified? Each mineral has characteristic properties that can be used to identify it.  Color  Streak: the color of its powder (can be different from its mineral color)  Luster: how light is reflected from a mineral’s surface  Hardness: Mohs hardness scale used to rank the hardness of minerals (1-10) A mineral can scratch any mineral softer than itself, but cannot scratch a mineral harder than itself.  Density: each mineral has a specific density.  Density = Mass/volume

 Crystal Structure: all the crystals of a mineral have the same crystal structure  Cleavage and Fracture: A mineral that splits easily along flat surfaces has the property called cleavage. A mineral that breaks apart in an irregular way has the property fracture.

How Do Minerals Form? Geode-  A crack or hollow forms in a rock  Water containing dissolved minerals seeps in  Crystalization slowly occurs  Geode is complete

Other Ways… Organic Minerals: Ex, ocean animals such as clams and corals produce shells and skeletons made out the mineral calcite. Minerals from Solutions: When elements and compounds that are dissolved in water leave a solution, crystallization occurs. Minerals from Magma and Lava: Minerals form as hot magma cools inside the crust, or as lava hardens on the surface. When liquids cool to solid state, they form crystals. Where Mineral Resources Are Found: Earth’s crust is made up of common rock-forming minerals.

Classifying Rocks! How Do Geologists Classify Rocks?  1. Mineral Composition and Color  2. Texture  Grain Size  Grain Shape  Grain Pattern

 3. Origin:  Igneous Rock – forms from the cooling of magma or lava  Sedimentary Rock – forms when small particles of rocks or the remains of plants and animals are pressed and cemented together  Metamorphic Rock – forms when a rock is changed by heat or pressure, or by chemical reactions.  See p225

The Rock Cycle Forces deep inside Earth and at the surface produce a slow cycle that builds, destroys, and changes the rocks in the crust. The rock cycle is a series of processes that slowly change rocks from one kind to another. See p228