Section 4.1What is a Mineral?Glencoe Earth ScienceGeology, the Environment and the Universe
IntroductionEarth’s crust is composed of about 3000 mineralsMinerals help form rocks and shape Earth’s surface
Mineral Characteristics• A mineral is a naturally occurring, inorganic solid with specific chemical composition and definite crystalline structure.• Naturally Occurring: The are made in nature not in a lab or factory.• Inorganic: They aren’t alive and never have been alive. For example salt is a mineral but sugar isn’t because sugar comes from a plant which is a living thing.• Solid: Has a definite shape and volume.• Chemical composition: Some are made from single elements like copper, silver and sulfur. The majority are made of compounds (two or more different types of elements). When the mineral is formed of a compound the ratio of each element is always the same.
Mineral Characteristics Cont.• Definite crystalline structure: A crystal is a solid in which the atoms are arranged in repeating patterns.• Crystals may take the shape of 6 major crystal systems: cubic, tetragonal, hexagonal, orthorhombic, monoclinic and triclinic
Examples of How Crystals GrowSample of crystal that grew in an Sample of crystal that grew in a open space restricted space
Minerals From Magma• Minerals can form from the cooling of magma • Magma is molten material found beneath Earth’s Surface. • Because of it’s density, magma is forced up to the cooler layers of Earth’s surface. • The type and amount of elements in the magma will determine what type of minerals will form. • The rate of the cooling will determine the size of the mineral crystals. • Magma that cools slowly will form larger crystals because the atoms have more time to rearrange • Magma that cools quickly will form smaller crystals because the atoms don’t have as much time to move around.
Minerals From SolutionOnce a given volume of water can no longer dissolve a solid, the If elements dissolve in a supersaturated solution minerals canwater becomes saturated with that solid. In nature if the waterbecomes supersaturated, or overfilled, with another substance, form when the water evaporates mineral crystals may begin to drop out of the solution
Mineral Groups• Silicates • Made up of silicon and oxygen (one silicon atom is bonded to three oxygen atoms) • They are 96% of minerals found in Earth’s crust. • Common examples are feldspar and quartz• Carbonates • Minerals composed of one or more metallic elements combined with CO2 (Carbon Dioxide) • Some have distinct colors (malachite and azurite) • Found in rocks like limestone, coquina and marble
Mineral Groups Cont.• Oxides • Compounds of oxygen and a metal • Examples include hematite and magnetite• Other Mineral Groups include: • Native Elements • Hydroxides • Halides • Sulfates • Sulfites