EarthSci: MINERALS AND ROCKS - EARTH MATERIALS AND PROCESSES
Volcanic or extrusive Igneous rocks
- Examples tuff and pyroclastic flow deposits (ignimbrite)
Plutonic or intrusive Igneous Rocks
- Examples: granite, diorite, gabbro
Plutonic or intrusive Igneous Rocks
- Phaneritic texture
Clastic sedimentary rocks
- are commonly classified based on particle size
Clastic sedimentary rocks
- are volcanic in origin (e.g. pyroclastics) and may have undergone some stages in the sedimentary processes that could be classified as sedimentary rock (e.g. volcanoclastic rocks).
Plutonic or intrusive Igneous Rocks
- causing slow cooling /crystallization
Non-clastic sedimentary rocks
- classified as evaporites (halite, gypsum and dolostone), precipitates (limestone) and bioclastics (coal, coquina)
Volcanic or extrusive Igneous rocks
- common textures: aphanitic, porphyritic (define groundmass vs phenocrysts), vesicular
Regional Metamorphism
- creates foliated metamorphic rocks
Non-clastic sedimentary rocks
- evaporation and precipitation from solution or lithification of organic matter
Volcanic or extrusive Igneous rocks
- examples: rhyolite, andesite, basalt
Regional Metamorphism
- examples: schist, gneiss
Volcanic or extrusive Igneous rocks
- fast rate of cooling/crystallization due to huge variance in the temperature between Earth's surface and underneath
Volcanic or extrusive Igneous rocks
- from solidified lava at or near the surface of the earth
Plutonic or intrusive Igneous Rocks
- from solidified magma underneath the earth
Clastic sedimentary rocks
- have the components of grains, matrix and cement
Contact metamorphism
- it creates non-foliated metamorphic rocks; an example is a hornfels
Contact metamorphism
- it occurs when a pre-existing rock gets in contact with magma which is the source of heat and magmatic fluids where metamorphic alterations and transformations occur around the contact / metamorphic aureole of the intruding magma and the rock layers.
Regional Metamorphism
- non-foliated rocks like marble also form through regional metamorphism, where pressure is not intense, far from the main geologic event
Regional Metamorphism
- occurs in a regional/large scale
Volcanic or extrusive Igneous rocks
- pyroclastic rocks: fragmental rocks usually associated with violent or explosive type of eruption.
1. Friedrich Mohs 2. Mohs Scale of Hardness
A German geologist/mineralogist named ______ in 1812 designed a hardness scale called the ____________
Amorphous
A mineral that do not have a crystal structure is described as ?
Metamorphism
Can involve changes in the physical and chemical properties of rocks in response to heat, pressure, and/or chemically active fluids
Saur TRUE
Can the color of a mineral can be different from its streak?
Fossil assemblages and stratification
Common sedimentary features include ____ and ____
Others - magnetism, odor, taste, tenacity, reaction to acid, etc.
For example, magnetite is strongly magnetic; sulfur has distinctive smell; halite is salty; calcite fizzes with acid as with dolomite but in powdered form; etc.
Weathering
Individual minerals can also display a variety of colors resulting from impurities from some geologic processes like ________.
Hardness
It is a measure of the resistance of a mineral to abrasion.
Color
It is the first impression in minerals but it is not very reliable because lots of minerals can occur in many different colors.
Crystal Form/Habit
It is the natural shape of the mineral before the development of any cleavage or fracture.
Mohs Scale of Hardness
It measures the scratch resistance of various minerals from a scale of 1 to 10, based on the ability of a harder material/ mineral to scratch a softer material.
Metallic
It's generally opaque and exhibit a resplendent shine similar to a polished metal
Streak
It's the TRUE color of a mineral in a powder form. It is inherent in almost every mineral and is a more diagnostic property compared to color.
Cleavage
It's the property of some minerals to break along specific planes of weakness to form smooth, flat surfaces.
Luster
It's the quality and intensity of reflected light exhibited by the mineral.
1. Plutonic Igneous Rocks 2. Volcanic Igneous Rocks
Molten rock material can solidify below the surface of the earth (_____ igneous rocks) or solidify at the surface of the Earth (_____ igneous rocks)
Stratification or layering
Results to a change in grain size and composition.
Igneous Rocks
Rocks that are formed from the solidification of molten rock material.
Rock Cycle
The constant recycling of minerals, how geologic processes occur both underneath and on the Earth's surface which allows a rock to change from one type to another.
Crystal Form/Habit
The external shape of a crystal or groups of crystals is displayed / observed as these crystals grow in open spaces.
Crystal Form/Habit
The form reflects the supposedly internal structure (of atoms and ions) of the crystal (mineral).
Igneous Rocks
The process of solidification involves the formation of crystalline solids called minerals.
Specific Gravity
The ratio of the density of the mineral and the density of water.
Fossil assemblages
The remains and traces of plants and animals that are preserved in rocks
Minerals
These are solid, inorganic substances that are present in nature and has a definite chemical composition.
Cleavage
These planes exist because the bonding of atoms making up the mineral happens to be weak in those areas.
Sedimentary rocks
They form at surface or near surface conditions.
Specific Gravity
This parameter indicates how many times more the mineral weighs compared to an equal amount of water (SG 1).
A. Plutonic or intrusive Igneous Rocks B. Volcanic or extrusive Igneous rocks
Types of Igneous Rocks?
A. Contact metamorphism B. Regional metamorphism
Types of Metamorphic Rocks?
A. Clastic sedimentary rocks B. Non-clastic sedimentary rocks
Types of Sedimentary Rocks?
Non-metallic
Vitreous (glassy), adamantine (brilliant/diamond-like), resinous, silky, pearly, dull(earthy), greasy, among others.
i. The test is easy. ii. The test can be done anywhere and anytime. iii. The test is convenient for field geologists with scratch kits who want to make a rough identification of minerals outside the lab.
What are the advantages of the Mohs scale?
i. The Scale is qualitative, not quantitative. ii. The test cannot be used to accurately test the hardness of industrial materials.
What are the disadvantages of the Mohs scale?
1. Color 2. Streak 3. Luster 4. Hardness 5. Crystal Form/Habit 6. Cleavage 7. Specific Gravity 8. Other (ex: magnetism, odor, taste, tenacity, reaction to acid, etc.)
What are the several different mineral properties?
a. Metallic b. Non-metallic
What are the two kinds of minerals?
Igneous, Metamorphic, and Sedimentary
What are types of rocks?
Cleavage
When minerals break evenly in more than one direction, cleavage is described by the number of ______ directions, the angle(s) at which they meet, and the quality of _____.
1. Metamorphic rocks 2. Metamorphism
____ are rocks that form through the transformation of preexisting rocks (igneous, sedimentary, or metamorphic rocks) through the process of ________
Plutonic or intrusive Igneous Rocks
gradual lowering of temperature is indicated by the movement of magma from depth to surface
Contact metamorphism
heat and reactive fluids as main factors
Regional Metamorphism
pressure is the main factor which occurs in areas that have undergone considerable amount of mechanical deformation and chemical recrystallization during orogenic event which are commonly associated with mountain belts
Sedimentary rocks
rocks that form through the accumulation, compaction, and cementation of sediments.