Transcript Rocks
Minerals Building blocks of rocks and our Earth. Chapter 29 section 3 What is A Mineral? Mineral - a solid, naturally-occurring, inorganic element or compound with defined chemical composition. They are also crystalline in structure. Based on regular arrangement of atoms or ions within it. Rock forming minerals very common on Earth’s surface The 20 most common make up 95% of Earth’s crust Quartz, and orthoclase feldspar are the most common Silicate minerals – minerals containing atoms of silicon (Si) and oxygen (O). Nonsilicate – minerals that do not contain Si. There are 6 groups. Crystalline Structure – natural solid with definite internal pattern. Large crystals show internal structure If crystal forms in UNRESTRICTED environment a single large crystal WILL develop. Crystal Identifying Minerals Characteristics of Minerals – minerals are identified by their properties. Color- the color of it. Color is unreliable Luster- the way light is reflected from fresh surface of the mineral Metallic: looks like polished metal. Nonmetallic: glasslike, waxy, pearly, brilliant (diamond), dull or earthy, and many more. Identifying Minerals Streak- color obtained when mineral is rubbed across the surface of an unglazed porcelain tile. Streak is more important than color mineral true color. Cleavage - tendency of mineral to split on flat surfaces. Fracture – tendency of mineral to break unevenly Identifying Minerals Hardness - Resistance of a mineral to scratching Moh’s Scale of Mineral Hardness. 19th century German mineralogist, Friedrich Moh. Know the chart on page 578. Identifying Minerals . Common materials to estimate hardness fingernail-hardness about 2.5 copper penny-hardness 3 to 3.5 steel nail-hardness 5 to 5.6 window glass-hardness 5.5 to 6 Rocks Types of Rocks Igneous Rocks Metamorphic Rocks Sedimentary Rocks Types of Igneous Rocks Intrusive: Formed underground by trapped, cooled magma, large mineral crystals Extrusive: Formed above ground when volcanoes erupt and magma cools, smaller mineral crystals. Examples of Igneous Rocks Intrusive Igneous Extrusive Igneous Granite Scoria Diorite Obsidian Sedimentary Rocks How They are Made Wind and water break down the earth Bits of earth settle in lakes and rivers Layers are formed and build up Pressure and time turn the layers to rock Sedimentary Rock Classification – composed of fragments (clasts) of pre-existing rock transported some distance from their points of origin Chemical – form when standing/trickling water evaporates, leaving dissolved minerals behind. Organic – an accumulation of sedimentary debris caused by organic processes. Plants and animals. Clastic Types of Sedimentary Rocks Sandstone Clastic Gypsum Chemical Limestone Organic Conglomerate Clastic Shale Clastic Metamorphic Rocks Rocks that have changed They were once igneous or sedimentary Pressure and heat changed the rocks 2 types: Regional and Contact Contact occurs near magma chambers Regional occurs where continents collide Types of Metamorphic Rocks Marble Gneiss Rocks Have Been Used For Many Years and For Many Things Rocks