Chapter II: Rock-Forming Minerals and Rocks Flashcards
What traits of minerals determine their physical properties?
Hardness is determined by the strength of the chemical bonds.
Density is determined by the weight of its atoms, and to some degree their structure.
Fracture Pattern is determined by the weakness of the crystalline structure.
What conditions produce various kinds of igneous rock?
Mafic igneous rocks are denser than felsic rocks due to the high atomic weight of iron atoms. Extrusive rocks are smooth due to their rapid cooling, conversely intrusive rocks are more granular due to their slow cooling.
What are the ways in which sedimentary rocks form?
Clastic sedimentary rocks form when sediments are deposited then compacted by the weight of sediments above them. Next they are cemented by fluids, causing minerals to precipitate and form the rocks.
Chemical Sedimentary rocks form when they are precipitated from water.
How do metamorphic rocks form from other rocks?
Composition and texture vary depending on degree of heat and pressure. 4 methods of metamorphism; Regional, Contact, Hydrothermal, and Burial.
How does an ion form from an uncharged atom?
Ions are formed when an uncharged atom gains or loses an electron(s) in order to form a more stable valence shell.
Silicates
Most abundant mineral family in Earth’s crust/Mantle. Basic building block of SiO4
Sedimentary Structure
Distinct arrangement of grains which reflects the method of deposition.
Why do most sediments formed by weathering consist of silicate minerals?
Because silicates make up the majority of rocks on earth.
Silliclastic Sedimentary Rocks
Consists of silicate grains produced by weathering and erosion
Regional Metamorphism
generally within hundreds of kilometers, caused by catastrophic events such as a meteor impact which creates the conditions necessary for metamorphism.
Contact Metamorphism
heat from an igneous intrusion bakes surrounding rock
Hydrothermal Metamorphism
hot, watery, fluids percolate through rocks to form metamorphic rocks
Burial Metamorphism
Deep burial of rocks produces the conditions necessary for metamorphism (i.e. Coal from plant material)
Ions
Retain their identity when dissolved in water. Enables chemical precipitates like salt.
Aragonite
Common minerals consisting of calcium carbonate (CaCO3);
Precipitates directly from shallow tropical seas as tiny needle shaped crystals and accumulates into carbonate mud.
Forms younger Limestone because it is unstable.
Calcite
Common mineral consisting of calcium carbonate (CaCO3);
Precipitates to form blocky, or tooth shaped crystals. Forms Limestone that can last much longer than Aragonite based Limestone.
Calcite
Common mineral consisting of calcium carbonate (CaCO3);
Precipitates to form blocky, or tooth shaped crystals. Forms Limestone that can last much longer than Aragonite based Limestone.
8 Major Mineral Groups
Silicates, Carbonates, Sulfates, Phosphates, Halides, Oxides, Sulfides, Native Elements.
Silicates
(SiO4)^-4 tetrahedra are basic units;
Mostly hard, except for mica and clay minerals, glassy/pearly luster;
Dominant mineral group in crust and mantle;
Carbonates
Positive Ions attached to (CO3)^-2;
soft, light colored;
Mostly sedimentary, but also marble (metamorphic);
Sulfates
Positive ions attached to (SO4)^-2;
Soft, light colored, water soluble;
Mostly sedimentary