Rocks And Minerals Flashcards
Layers of earth
Inner solid core
Outer liquid core
Lower solid mantle
Upper solid mantle
Asthenosphere
Lithosphere
Continental crust
Oceanic crust
Continental crust
Felsic (feldspar and silicon)
Made of Grannite and rhyolite
Older than oceanic crust
Thicker
Less dense
Oceanic crust
Mafic (magnesium, and iron)
Made of basalt and gabbro
Younger than continental crust
Thinner
More dense
Converging
Oceanic crust, subducts or sinks since it is denser than continental crust
Mineral deposits
Substantial natural accumulation of valuable minerals in places within the Earth‘s crust
Aggregates of a mineral or a group of minerals that can be extracted at present time or in future
Grade
Degree of concentration of a mineral content
Economic mineral deposits
Deals with application of concepts of economics in supply and demand of minerals and their resources
Mineral deposit
Mineral occur, occurrence of sufficient size and grade, which might be considered to have economic potential
It may or may not be mined for profit
Mineral occurence
Concentration of an economic mineral which is considered valuable
Ore deposit
Mineral deposit that has been tested and found to be of sufficient size grade and accessibility
It is mined for profit
Gangue
Unwanted impurities such as dust particles, soil, sand, limestone, earthly particles, mica, et cetera, present in the ore
Ore minerals classification
- Native (do not occur in combination with other elements)
- sulphide (occur in combination of metal + sulphur)
- oxides and hydroxide (occur as metal + oxygen)
- silicate
Examples of native ore minerals
In metals - gold, silver, platinum
In semimetal - bismuth, astatine, antimony
Nonmetals - carbon(graphite, and diamond), sulphur
Largest group of ore minerals
Sulphides
Examples of sulphide ore minerals
FeS2, ZnS, PbS, HgS, CuFeS2
Examples of oxides and hydroxides
Oxides = Fe3O4, Fe2O3, MnO2, TiO2
Hydroxides = Al(OH)3, MnO(OH)
Example of silicate
Quartz, olivine, muscovite and biotite micas
Four main geological process responsible for formation of rocks
- Igneous (exogenous)
- Metamorphic (exogenous)
- Sedimentary (endogenous)
- Surficial (endogenous)
What is exogenous?
Deep within the Earth
What is endogenous?
At or near the surface of earth
Magmatic process of rock formation
Hot liquid magma, cools and solidify to crystallise and form a mineral
Example chromite (chromium)
Hydrothermal process of rock formation
Hot aqueous fluids (hot water) acts as a medium for transportation and enrichment of certain elements which precipitates and forms economic minerals
Example Skarns (silicate)
Contact metasomatic process of rock formation
When magma chambers release gases that reacts with intrusive rocks, it forms new minerals
Example Grossularite, diopside, scapolite
Residual process of rock formation
When soluble rocks like limestone is removed from solution, it leaves behind in soluble minerals, concentrated as mineral residue
Example laterite
Placer process of rock formation
Surface weathering along with ocean river or wind, action, and gravity separation results in concentration of economic minerals
Example, gold, gemstones, platinum, pyrite, magnetite, et cetera
Feldspar is used in
Glass
ceramics
enamelware
soap
Iron blue is used in
Paint
Printing ink
Paper dye
Iron black is used in
Pigment
Polishing
Magnetic ink
Ground mica is used in
Paint
Joint cement
Roofing
Sheet mica is used in
Electronic equipment parts
Perlite is used inb
Building construction products
Quartz is used in
Pressure gauges
Oscillators
Resonators
Prism
Magnetite is used in
Steel production
Hematite is used in
Jewellery
Polishing
Pigments
Pyrite is used in
Treating iron deficiency
Anaemia
Covellite is used in
Lithium batteries’ cathode
Solar electric devices
Sphalerite is used in
Gemstones
Cosmetics
Galvanisation
Pharmaceutical
Helium is used in
Balloons
Element lithium is used in
Batteries
Element fluorine is used in
Toothpaste
Element phosphorus is used in
Match sticks
Element argon is used in
Bulb
Element cobalt is used in
Screws
Element nickel is used in
Coins
Element selenium is used in
Shampoo
Element tellurium is used in
CDs
Pyrolusite is used in
Colouring material in glass, pottery, and bricks
Coal origin
Remains of fossil plants
Types of coal
- Anthracite.
- Bituminous
- Sub bituminous
- Lignite
- Peat
Anthracite
Highest rank of coal
Shiny and black
Hard and brittle
Highest carbon percentage
Low impurity
Blue smokeless, flame on burning
Bituminous coal
Commonly composed of thin light and dark alternative bands
Shiny and dull
Second highest quality of coal
Mostly black
Lignite
Lowest energy content
Peat
Lowest carbon content
Consists more of organic matter, mineral, and water
Light brown in colour
Brown coal
Compressed peat
Origin of petroleum
Remains of prehistoric plants and animals
Various products out of petroleum
Gasoline
Kerosene
Liquidy, petroleum gas (LPG)
Diesel fuel
Paraffin wax
Petroleum jelly
Petroleum wax
Naphthalene
Origin of natural gas
Same as petroleum and coal
Remains of plants and animals
Products of natural gas
Liquified natural gas (LNG)
compressed natural gas (CNG)
What are rocks? And their types.
Rocks are mineral aggregates.
- Igneous rocks - cooling, and solidification of magma or lava.
- Sedimentary rocks - formed by sedimentation, deposition and cementation at surface of earth.
- Metamorphic rocks - make up La part of earth’s crust; brings changes in pre-existing rocks due to high temperature and pressure
Types of igneous rocks
a. Intrusive igneous rocks - large crystals crystallise below earth surface, eg. Granite, diorite
b. Exclusive igneous rocks- small crystals above the surface eg. Basalt, pumice
Types of sedimentary rocks
- Clastic - mechanical weathering debris eg. Sandstone, siltstone, etc.
- Chemical - dissolved materials that precipitate from solution eg. Limestone.
- Organic - accumulation of plant and animal debris eg. Coal, some dolomites.
Types of metamorphic rocks
- Foliated- layered rocks eg. phyllite, gneiss
- Non foliated - non-layered rocks eg. Marble, quartzite
Composition of majority of ocean floor
Basalt
Rock cycle
- rocks constantly go through several processes of physical and chemical changes
- Through rock cycle, three main rocks that is igneous, sedimentary, and metamorphic transfer from one type to another
- transition to Igneous happens when rocks are pushed deep under the Earth surface, they melt into magma solidify and become Igneous rock
- transition to sedimentary rocks occurs when due to weathering and erosion, original rock breaks down into smaller fragments and carries away dissolved materials. They are formed from deposits that accumulate on earth surface.
- transition into metamorphic occurs when rocks are exposed to high temperature and pressure that brings changes physically or chemically to form a metamorphic rock
Felsic igneous rock
Rich in silica and light coloured minerals
Mafic igneous rock
Rich in magnesium with iron and dark coloured minerals
Intermediate igneous rocks
Between felsic and mafic with both light and dark minerals
Ultra mafic igneous rocks
Very rich and high in iron and magnesium, but low in silica
Terminology for sedimentary rocks based on grain size and shape
Gravel = > 2 mm
Sand = 2 - 0.06 mm
Silt = 0.06 - 0.002 mm
Clay = < 0.002 mm
Contact metamorphism
Rocks that are heated by proximity to magma or lava eg. hornfels
Largest layer of earth
Mantle
How many main plates are there on earth surface?
12
What is plate boundary?
A plate boundary occurs when two plates come together
What are the three kinds of plate boundaries?
A. Convergent (mountains, or subduction)
B. Divergent (plates, moving in opposite direction)
C. Transform (plates, slide past each other)
History of earth
Earth was formed 4.543 billion years ago
Early earth had one super continent called Pangaea which was surrounded by one gigantic ocean called Panthalassa.
Then Pangaea broke into two new continents - Laurasia and Gondwanaland
Triple Junction was formed because of upWelling of magma that broke the crust in three directions and poured out Lava, creating a split in the crust.
Laurasia in present day is?
North America, Europe, and Asia
Gondwanaland in present day is?
South America, Antarctica, and Australia
Who is the father of geology and stratigraphy?
Nicolaus Steno
What is stratigraphy?
Arrangement and succession of strata or layers
What is law of superposition?
Within sequence of layers of sedimentary rock, oldest layer is at the base and that the layers are progressively younger with ascending order
What is cross cutting?
A feature (like a river channel) cutting into a layer must be younger than that layer
What is inclusion?
Material from an older layer can be reworked into a younger layer or vice versa
What are the types of stratigraphy?
Archaeo-stratigraphy
Litho-stratigraphy
Bio-stratigraphy
Pedo-stratigraphy
Who is the father of palaeontology?
Georges Cuvier
Palaeontology
- Study of history of life on earth based on fossils
- For a fossil thinner and lesser number of rings, indicate struggle for survival and unfavourable conditions
-palaeontology can be divided into two for vertebrates and invertebrates
What is Amber in palaeontology ?
It is another example of a fossil
It is a hardened fossilised tree raisin
Permineralisation or petrifaction
mineral rich water percolates through sediment and precipitates out the mineral in empty spaces
Two famous examples of fossil showing exceptional preservation
- The Burgess Shale in Canada - remains of first shelled creatures from ‘ Cambrian explosion of life’
- The Solnhofen limestone in Germany - where softbodied jellyfish and earliest bird archaeopteryx is preserved with complete feathers.
Index fossil
A person with characteristic of a particular span of geological time or environment
Because they were so abundant and widespread during a short period of geological time, their presence helps date rocks from that period
Ammonites - index fossils for the Jurassic
Trilobites - index fossils for the Cambrian
Graptolites - index fossils for the Silurian
Impregnation/ embedding
similar to petrifaction, but fossil is also surrounded by mineral rich water in this
Mineralisation
complete replacement of original material by new material happens in this.
Compression
high-pressure from compression expels volatiles and can cause a dark imprint of organism left behind rock, commonly occurs in ferns and leaves.
Exceptional preservation
soft body parts are also preserved in. This type usually occurs in environment where there is no oxygen and organism is unable to decay and disintegrate.
Carbonisation
a chemical reaction where water transforms organic material of plant or animal to a thin film of carbon. Nitrogen and gases driven off, leaving and outline of organism.
Fossil in tots
when organism is preserved without any change in morphology and composition
Body fossil, and its types
When part of an organism, plant or animal, is preserved, it is called body fossil
1. Altered body fossil (change in composition)
2. Unaltered body fossil (no change in composition)
Trace fossil
When traces of an biological activity of an organism or preserved
Eg. Walking, crawling, resting, grazing traces
Mold and cast
Mold is always negative relief, whereas cast is always positive relief
Mold depicts outer surface features of an object or organism, whereas cast is a cavity filling structure and depicts internals
Coprolites
Fossil dung (faeces) and stomach contains in soft sediment, that later forms solid sedimentary rocks
Also known as fossilised drooping
Pseudo fossils
In organic objects or markings or impressions that might be mistaken for fossils
Sub fossil
Remains whose fossilisation process is not complete
Living fossil
Any living species, which resembles species that is only known from fossils and has no living relatives
Eg for plant is Wollemi pine
For animal is horseshoe crab
What are the three general approaches by scientists for determining the age of fossils?
- Relative dating.
- Index fossils
- Magnetism.
Age of fossils
To establish age of rock or a fossil researchers, use some type of clock, such as certain elements like potassium and carbon (radioactive decay), also radiometric dating methods based on natural radioactive decay and other methods, such as electron spin resonance (ESR) and thermoluminescence
Radioactive decay
occasionally, unstable isotopes will change its number of protons, neutrons, or both. This change is called radioactive decay. Radiation is by product of radioactive decay.
Radioactive decay
Voc occasionally, unstable isotopes will change its number of protons, neutrons, or both. This change is called radioactive decay.
Radioactive isotopes and how they decay through time
Carbon has three isotopes
12 C6 , 13 C6, 14 C6
Out of these 12 C6 and 13 C6 are stable isotopes
But 14 C6 is unstable, radioactive parent isotope
It will undergo radioactive decay and form 14N7 which is stable, daughter isotope
Because 14 C6 is unstable, it undergoes radioactive decay over time to become stable, 14N7
Half life of radioactive isotope
The amount of time it takes for half of parent isotope to decay into daughter, isotope is known as half life of radioactive isotope
Normal and reversed polarity
Through geologic times, earth‘s magnetic field has switched causing reversals in polarity
When geographic north and magnetic north are on the same side, it is normal polarity
When geographic north and magnetic South are on the same side, it is reversed polarity
Combined observations of this type has led to development of geomagnetic polarity time scale (GPTS) which is divided into periods of normal polarity and reversed polarity
Index fossil matric dates, help to distinguish between different eras or periods of reversed polarity
Relative dating
Tell us how old something is in relation to other objects
But cannot provide a year or specific date of use
Methods include stratigraphy, seriation, fluorine dating, et cetera
Absolute dating
Provides a specific calendar year for the fossil or rock
Methods include radiocarbon, dendrochronology, thermoluminescence
Father of modern geology
James Hutton
U 234 / Th 230
Used to establish ages
O 18/ O 16
Used to determine climate if it is, warm, or cold
