Rocks and Minerals

I. Rocks vs Minerals A. Rock – solid part of earth, make up lithosphere B. ALL rocks are made of minerals 1. Monomineralic – rocks made up of only ONE mineral 2. Polymineralic – rocks made of several (3 or more) minerals

II. Definition of a Mineral A. Naturally occurring B. Solid at normal earth surface temperatures C. Atoms are arranged in an orderly, repetitive pattern (crystals) D. Made of 2 or more elements E. Generally considered inorganic (not from living things, exception = calcite in seashells)

III. Silicates A. Most common group of minerals B. Made up of oxygen and silicon C. Silicon-Oxygen Tetrahedron – basic unit of structure of ALL silicates

III. Silicates (cont) D. Most common elements in lithosphere 1. By volume = Oxygen 94% 2. By mass = Oxygen 46%, Silicon 28%

III. Silicates (cont) E. Physical properties of minerals are determined by the arrangement of the atoms

IV. Mineral Identification A. Color – NOT very useful since most minerals can be found in MANY different colors

IV. Mineral Identification (cont) B. Luster – way it shines 1. Metallic – shines like metal 2. Non-metallic – dull, pearly, earthy

IV. Mineral Identification (cont) C. Streak – color of powdered mineral 1. Scratch on streak plate and note color 2. Some have NO streak if very hard

IV. Mineral Identification (cont) D. Hardness – depends on arrangement of atoms 1. Graphite = 1 2. Diamond = Both made of carbon, but arranged differently

IV. Mineral Identification (cont)

E. Cleavage – does it break along flat surfaces 1. Cleavage – breaks with flat surfaces 2. Fracture – shatters with NO flat surfaces 3. Determined by arrangement of atoms

IV. Mineral Identification (cont)

F. Density = Mass / Volume G. Taste – Halite tastes salty (rock salt) NEVER - EVER TASTE ANYTHING IN SCIENCE CLASS! F. Reaction with HCl 1. Some minerals bubble with HCl (Calcite)

IV. Mineral Identification (cont)

V. Igneous Rocks A. Form when molten (hot, melted) rock solidifies as it cools forming crystals (crystallization)

V. Igneous Rocks (cont) Magma – molten rock below surface Extrusive (volcanic) – surface -Rapid Cooling -Small Crystals -Fine Texture Lava – molten surface

V. Igneous Rocks (cont) B. Extrusive Examples Rhyolite Basalt Vesicular Basalt

V. Igneous Rocks (cont) Intrusive (Plutonic) – forms below surface (inside) -Slow Cooling -Large Crystals -Coarse Texture

V. Igneous Rocks (cont) C. Intrusive Examples Granite Gabbro Pegmatite

V. Igneous Rocks (cont) D. Naming Igneous Rocks – based on composition, texture, color and density

V. Igneous Rocks (cont)

VI. Sedimentary Rocks A. Form with the help of water B. Types 1. Clastic – (fragmental) a. formed when sediments are deposited and then compressed and cemented together b. Found in layers (stratified)

VI. Sedimentary Rocks (cont) Sandstone Conglomerate Shale

VI. Sedimentary Rocks (cont) 2. Evaporites (chemical) a. Formed when dissolved chemical substances form rock b. As water evaporates, dissolved materials come out of solution

VI. Sedimentary Rocks (cont) Limestone Dolostone

VI. Sedimentary Rocks (cont) 3. Organic Sedimentary Rocks a. Form either directly or indirectly from living things b. Coal – formed from trees and other plants in swampy areas millions of years ago c. Fossiliferous Limestone – shells of animals are cemented together

VI. Sedimentary Rocks (cont) Coal Fossils Coquina

VII. Sed Rocks Show Past Env A. Grain Size – shows how deep water was in area where rocks formed 1. Large grains – shallow water 2. Small grains – deep water 3. Shale on top of Conglomerate = shallow water followed by deep water (bottom rock is older)

VII. Sed Rocks Show Past Env B. Fossils 1. Remains, imprints or traces of ancient plants or animals 2. Found ONLY in sedimentary rocks 3. Tells the kinds of conditions that were there when the sediments were deposited

VII. Sed Rocks Show Past Env Fossilized Ferns Fossilized Trilobites

Sedimentary Rock ID Chart

VIII. Metamorphic Rocks A. “Changed Rocks” B. Form from other rocks (sed, ign or meta) as a result of heat, pressure and/or chemical activity C. Rocks recrystallize w/o melting

VIII. Metamorphic Rocks D. Classes 1. Regional – formed by forces over LARGE areas a. Deep within Earth, high temp and pressure from mountain building 2. Contact – formed where molten rock contacts existing rock a. High temp changes rock

VIII. Metamorphic Rocks (cont)

E. Changes caused by metamorphism 1. Banding – minerals concentrated into zones of different colors (looks like broken layers) Gneiss

Mica Schist

VIII. Metamorphic Rocks (cont) 2. Distortion – twisting of rock structure

VIII. Metamorphic Rocks (cont) 3. Increased Density – rock particles are squeezed closer together 4. Chemical Changes – new minerals may form

VIII. Metamorphic Rocks (cont) F. Common Rocks Marble Slate Gneiss Schist

VIII. Metamorphic Rocks (cont)

A. Three types of rocks are Igneous, Sedimentary and Metamorphic B. Rocks are classified based on their origin C. Interactions with air, water and land can cause rocks to change to a different type D. This continuous process is the rock cycle Rock Cycle

IX. Rock Cycle

X. Classifying Rocks A. Sedimentary – earthy (dull) and show layers, may contain fossils B. Igneous – Glassy and/or contains crystals, NEVER has fossils, could have gas pockets (vesicular) C. Metamorphic – may show banding (fake layers) and be twisted or folded, intergrown crystals