Chapter 2: Rocks and Minerals Section 1: Minerals

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A. Minerals - inorganic, solid materials found in nature, with a particular chemical makeup and an orderly arrangement of atoms. (inorganic means they are NOT formed by plants or animals – they were never alive) 1. Rocks are usually made of two or more minerals. 2. Minerals can form from magma or through evaporation or precipitation. 3. Mineral formation clues include size and how mineral crystals fit together.

B. Properties – characteristics used to identify minerals. Minerals have an orderly arrangement of atoms and often form crystals in a variety of shapes and sizes

B. Properties – characteristics used to identify minerals. 1. How they break a. Some minerals have cleavage, they split into thin sheets. b. Some minerals have fractures, breaking into rough edges.

B. Properties – characteristics used to identify minerals. 2. Color and Streak – the color of a powdered mineral can help identify minerals 3. Luster describes how light reflects from a mineral’s surface. a. Metallic luster – shiny like a metal b. Non-metallic luster - pearly, glassy, dull, or earthy

Mineral Hardness Hardness of Common Objects Talc 1 (softest) Gypsum 2 fingernail (2.5)  Calcite 3 copper penny (3.0) Fluorite 4 iron nail (4.5)   Apatite 5 glass (5.5) Feldspar 6 steel file (6.5) Quartz 7 streak plate (7) Topaz 8 Corundum 9   Diamond 10 (hardest) 4. Mohs hardness scale tells which minerals are the softest (1) and which are hardest (10) a. arranged in order of which material scratches another b. Diamonds are the hardest mineral

5. Specific gravity – compares the weight of a mineral with the weight of an equal volume of water. 6. Some minerals have unusual properties. a. Magnetite is magnetic b. Calcite has double refraction and fizzes in the presence of dilute acids

2. Gems are minerals that are rare and can be cut and polished. C. There are more than 4000 known minerals, but only about 2 dozen are commonly found in rocks. 1. 2 main types of minerals: silicates (containing silicon and oxygen) and carbonates (containing carbon and oxygen) 2. Gems are minerals that are rare and can be cut and polished. a. Gems are formed under special conditions - for example diamonds are formed deep in Earth’s mantle and brought to the surface by volcanoes. b. Some gemstones can be made synthetically in laboratories but they are not as valuable.

3. Ores are minerals that contain enough of a useful substance to be sold for a profit. a. Many metals humans use come from ores. b. Ores must be processed to extract the minerals c. Metal should be reused and recycled as often as possible because minerals take millions of years to form and are a nonrenewable resource.

MAIN IDEAS 1) What is the difference between a mineral and a rock? -A MINERAL IS A NATURALLY OCCURRING, INORGANIC SOLID WITH A DEFINITE COMPOSITION AND AN ORDERLY INTERNAL ARRANGEMENT. -A ROCK IS MADE OF TWO OR MORE MINERALS 2) What are the properties that are COMMONLY used to identify minerals? COLOR, LUSTER, STREAK, HARDNESS, CLEAVAGE/FRACTURE, MAGNETISM