Solid Earth materials:

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Isabel Fleming
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1 Solid Earth materials: Elements minerals rocks Nonuniform distribution of matter Molten core Contains most heavy elements Iron, nickel Thin surface crust Mostly lighter elements 8 elements make up 98.6% of crust Rocks and minerals make up solid crust materials

2 Minerals Earth science definition: a naturally occurring, inorganic solid element or compound with a crystalline structure Must have regular, repeating pattern Example: halite (NaCl)

3 Crystal structures Can be made up of one or more kinds of element Diamond - carbon only Quartz - silicon and oxygen Classification Based on surface symmetries Six major systems: isometric, hexagonal, tetragonal, orthorhombic, monoclinic and triclinic

4 Silicates and nonsilicates

unit Four major arrangements 1. Isolated tetrahedrons 2.

5 Silicates Contain mostly silicon and oxygen Make up 92% of Earth s crust Based on silicon-oxygen tetrahedral unit Four major arrangements 1. Isolated tetrahedrons 2. Chain silicates 3. Sheet silicates 4. Framework silicates

6 Nonsilicates No silicon-oxygen tetrahedrons in crystalline structure Make up remaining 8% of Earth s crust Eight groups of nonsilicates 1. Carbonates (limestones, i.e. shells) Most abundant; secreted by organisms 2. Sulfates (evaporites) 3. Oxides (industrial minerals) 4. Sulfides (industrial metals) 5. Halides (salts) 6. Phosphates (fertilizer) 7. Hydroxides (weathered minerals) 8. Native elements (precious metals)

7 Mineral forming processes Formation in two liquid environments most common 1. Water solutions Crystals form from highly concentrated ions 2. Magma Molten rock from which minerals can crystallize Can happen below or above Earth s surface Lava: magma forced out to the Earth s surface Important factors Temperature Pressure Time Chemical Composition Glass (non crystalline) Rapidly cooled solid lacking a crystalline structure

8 Silicate Minerals formed at high temperatures, i.e. in magmas Bowen s reaction series Silicate crystallization sequence Ferromagnetic silicates crystallize at higher temperatures Minerals crystallizing later are progressively richer in silicon Explains variation in the mineralogy of igneous rocks and how so many different kinds of rocks can be made from a single magma

9 Rocks Aggregation of one or more minerals and perhaps other materials Minerals are physically combined to make rocks Most rocks are silicates, i.e. made of silicate minerals Classification scheme Based on how rocks were formed Three main groups 1. Igneous 2. Sedimentary 3. Metamorphic

10 Igneous rocks Formed from magma above or below Earth s surface All rocks were at one time igneous rocks Cooling rate determines the texture Intrusive igneous rocks Formed beneath surface Slow cooling produces large crystals Coarse grained Extrusive igneous rocks Formed from lava on surface Rapid cooling produces small crystals

11 Igneous rock classification Two factors 1. Composition 2. Texture Nonferrous composition on left of figure: Felsic Low in density Light in color Granite: most common example Ferromagnetic composition on right: Mafic Greater density Darker color Example: basalt

12 Types of Sedimentary Rocks Detrital Chemical Organic Limestones, cherts etc Clastic Texture Sandstones, shales etc. Crystalline Texture Evaporites etc.

13 Sedimentary rocks clastics Formed from particles or dissolved materials from previously existing rocks Sediments Accumulations of silt, sand or other materials that settled out of water Clastic sediments Accumulated from rocks at various stages of breaking down

14 Sedimentary rocks Chemical sediments Formed from dissolved rock materials Three sedimentation paths 1. Chemical precipitation from solution 2. Crystallization from evaporating water 3. Biological sediments

15 Lithification The rock-forming process Two main parts 1. Compaction Reduces thickness of deposit Squeezes out water 2. Cementation Spaces between sediment particles filled with chemical deposit Chemical deposit binds particles together

16 Metamorphic rocks Previously existing rocks changed by heat, pressure or hot solutions into distinctly different rock Causes associated with geologic events Movement of the crust Heating and hot solutions from magma intrusion Temperatures must be high enough to cause recrystallization, but not melting

17 Progressive metamorphism of a shale Shale

18 Progressive metamorphism of a shale Slate

19 Progressive metamorphism of a shale Phyllite

20 Progressive metamorphism of a shale Schist

21 Progressive metamorphism of a shale Gneiss

22 The rock cycle Rocks transformed into new types by Earths interior and exterior dynamical processes Moving continents Seas advance and retreat Weathered and eroded by wind and rain

Rocks and Minerals. Tillery, Chapter 19. Solid Earth Materials

Rocks and Minerals. Tillery, Chapter 19. Solid Earth Materials Rocks and Minerals Tillery, Chapter 19 Science 330 Summer 2007 No other planet in the solar system has the unique combination of fluids of Earth. Earth has a surface that is mostly covered with liquid