rock cycle and minerals (LEC 2) Flashcards
two broad areas of geology
historical geology
physical geology
sub-disciplines of geology (6)
Structure Geology
Environmental Geology
Geochemistry
Paleontology (biology)
Volcanology
Hydrogeology
rock is an aggregation of minerals, what is an aggregation
each mineral retaining its own identity
what causes weathering
Weathering:
* wind
* water waves
* running water
what is lithification
lithification: compaction and cementation
what is metamorphism
metamorphism: change in chemical and physical properties due to temperature and pressure
what are the five requirement to be officially a mineral
- naturally formed
- solid, at surface temperature and pressure
- crystalline structure, regular interior structure (its atoms must be
arranged in definite pattern) - inorganic
- chemical composition either fixed or varies within certain limits
most minerals are a combination of two or more elements, some minerals consist entirely from one element, name some
diamond and graphite are made from carbon, gold, sulphur
most minerals are a combination of two or more elements joined (via chemical bonds) to form…….
a compound
most minerals are a combination of two or more elements joined (via_________) to form a compound
chemical bonds
types of chemical bonds
- ionic bonding
- covalent bonding
- metallic bonding
- van der waals bonding
strongest chemical bond
covalent bonds
what are polymorphs
minerals that have the same chemical
composition but different structure
which results in different physical
properties
example of polymorphs
graphite and diamond (both consist of carbon)
minerals can be transformed from one to another if the surrounding ________ and ________ changed
temperature and pressure
how can we identify minerals
how it looks (color, luster), breaks,
feels, smells, tastes
why do we use physical properties, not chemical properties or the interior structure
because the chemical composition and/or interior structure are difficult to determine without sophisticated equipment
what is lustre
the quality of light reflection from the surface of a mineral
what does vitroeus mean
bright as in glass and it is transparent
although colour is often obvious, it is not always useful in mineral identification, why and give an example of a mineral
slight impurities in the mineral give variety of colors
fluorite and quartz
what is a streak
- it is the color of mineral in powdered form
- often useful in mineral identification
- scratching the mineral across a steak plate
metallic minerals have a ________ streak
nonmetallic minerals have a ________streak
dark
light coloured
what is a crystal habit
crystal habit refers to the external expression on a mineral that
reflects the orderly internal structure
do all minerals have crystal habit
no, when mineral formation is interrupted by space restrictions, it will not have crystal habit, i.e. the crystal faces will not be similar to the internal structure
what is hardness
a measure of resistance to abrasion or scratching by other substances
describe the moh’s scale
> 5.5 …………… hard
3 to 5.5 ……… moderate
< 3 ……………. soft
mohs scale of a fingernail
2.5
mohs scale of a penny
3.5
mohs scale of a construction nail
5.5
what is a cleavage
the tendency of mineral to break along
plane(s) of weak bonds, they have unequal chemical bonds in all directions
what is a fracture
the tendency of mineral to break irregularly,
producing uneven fracture, they have equal chemical bonds in all directions
name some uncommon physical properties of minerals
magnetism
reaction with HCl
taste
odour
feel
how many elements make up more than 98% of the of earth’s crust and which two make up the most
8
oxygen and silicon
minerals are classified into small number of groups (7 groups) based on their chemical composition, silicates is one of them. what are the types of silicates
ferromagnesian: minerals that contain iron and magnesium
nonferromagnesian: minerals that don’t contain iron and magnesium
