2.1 Minerals And Rocks Flashcards
Minerals
Building blocks of rocks
Mineral Physical Properties
Hardness Cleavage Solubility
What is Hardness?
Resistance to abrasion
What is Cleavage?
Tendency of a mineral to break along flat surfaces/plane
What is Solubility?
Erosion through chemical process
Rock Characteristics
Type Age Place Structure
What rock types are there?
Igneous Sedimentary Metamorphic
What is younger? Rock or Soil?
Soil. If soils are around for long enough they become a rock
What influences rock properties?
The process of the rock formation
What is an igneous rock?
Solidified from molten material (magma) Volcanic
What are the Volcanic Processes?
Lava tephra pyroclastic flows
What does explosive activity form?
A range of rock types - Tephra
What does effusive activity (magma coming to the ground surface) form?
Crystalline igneous rocks
How are plutonic rocks exposed?
Through uplift and erosion
How are plutonic rocks formed?
Formed at depth within the crust
What is a porphyritic crystal?
Large crystals in a fine-grained matrix - different rates of cooling over time
What is the cooling period for phaneritic crystals?
(coarse grained) slow cooling centuries+
What is the cooling period for aphanitic crystals?
(fine grained) (rapid) days to months
What are the different Rock Textures?
Fine grained (aphanitic) Coarse grained (phaneritic) large crystals in fine grained matrix (porphyritic)
What does extrusive mean?
Above earth’s surface
What does intrusive mean?
Below earth’s surface
What is a sub-volcanic Igneous rock?
The transitional rock between plutonic and volcanic
How are Volcanic Rocks formed?
In a low-pressure environment and fast cooling + extrusive
How are Plutonic Igneous Rocks formed?
In a high-pressure environment and slow cooling + intrusive
What is magma?
Molten rock which is less dense than the surrounding rock so rises buoyantly
What are the types of lava?
High Viscosity and Low Viscosity
What are the qualities of high viscosity lava?
Slow flow, Traps gas and forms vesicles
What are the qualities of low viscosity lava?
Flows easily Releases gas - minimizes vesicles
What is Tephra?
Fragmented material produced by a volcanic eruption
What are the consequences of explosive tephra activity?
Deposits - Hot rocks and welding on landing - sedimentary process turning rock fragments into rock over time
Pumice qualities
Lightweight porous crushable small fragments from volcanic eruption process
What are Ignimbrites?
Pumice tuff and lithics deposited by pyroclastic flow (hot tephra material flowing away from the volcano)
What are the types of ignimbrites?
Welded (vesicular and low density at shallow depths) and poorly-welded (non-vesicular and dense at greater depths)
What are the types of Sub-Volcanic rocks?
Dyke and Sill
What is a Dyke Rock?
Cutting across surrounding rock layers
What is a Sill Rock?
Parallel to surrounding rock layers
What rock has the most desirable engineering properties and why?
Intrusive and crystalline extrusive rocks. Strong - stable - little movement of water
What does weathering of volcanic deposits produce?
Problematic clay deposits
What rocks are highly variable in strength?
Volcanic rocks
What is Sedimentary?
Mechanically and organically deposited or lithified in place
What influences the sedimentary rock characteristics?
Composition of sediments - environment of deposition and transportation mechanism
What is the lithification process?
The process of turning loose sediment into solid rock through compaction and cementation
What are the sedimentary rocks produced from?
Pre-existing rocks = weathering and erosion. biological sources = dissolution and precipitation
What are the Sedimentary Rock Groups?
Clastic Biogenic Chemical Volcaniclastic Mixed
What is a Clastic Sedimentary Rock?
Formed from fragments of pre-existing rocks and minerals
What is a Biogenic Sedimentary Rock?
Sedimentary rock formed from the accumulation of organic remains
What is a Chemical Sedimentary Rock?
Formed from the precipitation of minerals from water
What is a Volcaniclastic Sedimentary Rock?
Sedimentary rock formed from volcanic material such as ash lava fragments and volcaniclastic debris
What are the general processes of Sedimentary Rock?
Weathering. Erosion & Transportation. Deposition. Accumulation and Lithification
What are the steps in the Lithification Process?
Soils to Compaction to cementation and more cementation
What are the clastic classifications?
Composites size shape sorting
Which rock deposit is generally the lowest?
Sedimentary
How does weathering affect exposed Sedimentary deposits?
Loss of strength and stability
What is metamorphic?
Heat or pressure changing one rock to another type
How are Metamorphic Rocks formed?
From pre-existing rock deposits. where the original is either modified or destroyed
Why do Metamorphic Rocks form?
As a result of heat and pressure
What does it mean when a Metamorphic Rock is formed?
New minerals. new structures
What is the Metamorphic process?
Contact - high heat. dynamic - deformation and pressure. regional - high heat and pressure
What are the characteristics of Metamorphic rocks?
Granular similar to igneous rocks. foliated - grain flattening or stretching - a non-uniform pressure is applied to the rock
How does the Metamorphic rock change properties?
Through temperature and pressure
Which Metamorphic rock is strong and stable?
Granular
Which Metamorphic rock is weaker along the planes?
Foliated
