The "Need to know" on MINERALS1. A mineral is a naturally occuring, inorganic, solid. (It was never alive or produced by humans)2. A mineral has a definite chemical composition and molecular structure.3. Minerals are classified based on their physical and chemical properties, chemical composition, and structure.4. The physical properties of minerals are usually due to the internal arrangement of atoms.5. The six main physical properties are color, streak, luster, hardness, cleavage, and fracture.6. Less common properties are things like taste, magnetism, and reacting with acid.7. Color is easiest to observe, but least useful. (Many are the same color, or the same mineral might be many colors!)8. Streak is the color of the mineral in a powdered form left on a tile. The streak is often a different color than the mineral, making it a useful tool for identification.9. Luster is the way a mineral reflects light. Metallic minerals appear very shiny and metal like, whereas nonmetallic minerals appear dull and have no metallic shine.10. Hardness of a mineral is its resistance to being scratched. Relative hardness is determined using ten minerals that make up "Moh's Scale." Talc is softest, diamond is the hardest. Mineral hardness is often compared to glass, a hardness of 5.511. Cleavage is the tendency of a mineral to split along one or more flat surfaces.Halite shows cleavage in three directions, and splits into cubes:12. Fracture applies to minerals that do not have cleavage. They break unevenly.13. Most of Earth's crust is made up of the following elements (from your ESRT):Oxygen and Silicon are most abundant.14. The structure of minerals refers to the arrangement of atoms. The two most common elements in the crust are silicon and oxygen, and they combine to make the "Silicon-oxygen tetrahedron":15. The back cover of your ESRT is loaded with mineral information!
Last Modified on October 11, 2011