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DOC ______ MINERAL NOTES Mineral- a naturally occurring, inorganic, crystalline, solid with a definite chemical composition. A substance is a mineral if it: 1. is solid 2. Was formed in nature (not made in a lab) 3. Is inorganic (not living) 4. Has atoms or molecules that all have the same crystal pattern 5. Has the same chemical composition throughout Three Ways Minerals Can Form 1. Evaporation - when water evaporates, minerals are left behind 2. Heating/cooling - magma cools and elements and compounds aggregate together to form minerals 3. Pressure - intense pressure breaks the bonds between compounds and the atoms recombine to form new bonds and compounds The Earth’s Crust Minerals come from the Earth’s crust. About 4000 minerals have been identified, but 98.5% are made of only eight elements (silicon, oxygen, aluminum, iron, calcium, sodium, potassium, and magnesium). 92% of all minerals in the crust contain silicon and oxygen Question: 75% of the crust is silicon dioxide. In large pieces it is called quartz. In small pieces it is called sand. Why would so much of the earth’s surface be covered in silicon dioxide? Other Terminology Rocks - mixtures of minerals Ore - what we call rock that contains minerals that can be mined Alloys - result when two minerals are combined (copper + zinc = brass; copper + tin= bronze) Classification of Minerals Some elements occur naturally but do not combine to form compounds. These are called native elements. Some examples of these include gold, copper, and sulfur. Others form compounds and are grouped based on what elements are present (see your Mineral Families chart!). Examples of these families are Oxides, Halides, Sulfides, Carbonates, Sulfates, and Silicates. The Silicates is the largest family of minerals.