Transcript I. Minerals
Aim: What is a Mineral? Do Now: Minerals are used in our everyday lives. In your notebook, try to think about and list the ways minerals are used by you and me every day. I. Minerals: are classified as… a. Naturally occurring b. Solid substance c. Orderly crystalline structure (specific shape) d. Definite chemical composition (the elements that it is made of) e. Inorganic (not living) II. How do Minerals Form? 1. Crystallization (to form a crystal) - hot material (magma/lava) cools, forcing elements within to combine and harden forming minerals. Pyrite Graphite Galena 2. Precipitates/Evaporites - solid substances dissolved in water are left behind to form crystals when the water evaporates. Like Rock Candy or the ring around your bathtub Salt Flat - Halite Limestone Cave 3. Hydrothermal Solutions - Very hot solutions cause chemical reactions with existing minerals to form new minerals (recrystallization). Pyrite Quartz III. Silicon-Oxygen Tetrahedron - Most abundant atomic structure in Earth’s crust. (there is a lot of it) - Found in Quartz (sand) and makes quartz very strong (resistant to breaking) Review Questions: 1) What are the five characteristics of all minerals? Minerals are naturally occurring, inorganic, solids, with definite crystal shape and definite composition. 2) Where does the material come from to undergo crystallization? The material comes from the inside of the Earth or a volcanic eruption. The material has to be extremely hot! 3) Describe the process of the formation of a precipitate. Material needs to be dissolved in water. Later, the water is evaporated leaving the mineral behind. Solid materials can not be evaporated like water. Aim: What Properties Help Identify Minerals? Do Now: How can a scientist tell the difference between different minerals? List some of the properties you would look for to classify a mineral. Use your ESRT page 16 to help determine useful properties. I. Properties of Minerals Depend on: 1) The chemical composition of the mineral. (the elements it is made up of) 2) How the mineral’s atoms are arranged internally (structure). Non-Metallic We will take notes on each section of this table Take out Page 16 of your ESRT 1. Color (least significant property) - cause by impurities that can affect the color of any mineral. Why is color the least significant property? Quartz Calcite Talc Halite 2. Streak - the color of a mineral in its powdered form. - found by rubbing a mineral across a streak plate (a piece of porcelain.) - A minerals streak is identified as either; Color – any color Colorless – clear, white or no streak 3. Luster - describes how light is reflected from the surface of a mineral. Pyrite Galena Metallic Looks like metal Sulfur vs. Feldspar Non-Metallic Doesn’t look like metal 4. Crystal Form – Shape of the mineral Garnet Calcite Quartz 5. Hardness - the resistance of a mineral to being scratched compared to known objects on Mohs scale of hardness. (arranged from 10 (hardest) to 1 (softest)) - determined using a glass plate. 1. If it scratches the glass, then the mineral is harder 2. If it doesn’t scratch the glass, then the mineral is softer. 6. Breakage - the tendency of a mineral to break apart into pieces. A) Cleavage - Minerals appear to have right angles, flat surfaces, boxed appearance. Mica Calcite b) Fracture - the uneven breakage of a mineral. Sulfur Quartz 7. Distinctive Properties of Minerals - Some minerals can be recognized by other distinctive properties (magnetism, smell) - Effervescence (bubbling) using Hydrochloric Acid indicates the presence of calcium (Calcite.)