Week 1 and 2

Question 1

What is a Unit Cell?

Answer 1

The smallest unit which, when repeated in 3D will build the crystal structure.

Question 2

What are the 3 types of Unit Cell?

Answer 2

Simple Cubic, Body-centred Cubic and Face-centred Cubic

Question 3

What is twinning?

Answer 3

Two separate crystals are inter grown and share some common points in the crystal lattice.

Question 4

What are the 4 types of twinning?

Answer 4

Rotational, Simple, Multiple(lamellar) and Cyclic.

Question 5

What is cleavage?

Answer 5

Where atoms are located at regular positions within the crystal lattice. Minerals can have single(sheet silicates) or multiple(pyroxenes and amphiboles) planes of cleavage.

Question 6

What are mafic minerals?

Answer 6

Dark coloured minerals rich in Magnesium and Iron.
Eg Olivine, Pyroxenes, Amphiboles and Biotite.

Question 7

What are Felsic minerals?

Answer 7

Light coloured minerals rich in Silicon and Aluminium. Eg Quartz, Feldspars and Muscovite.

Question 8

What are isomorphic and polymorphic minerals?

Answer 8

Isomorphic- Different chemical composition but similar structure
Polymorphic- Same chemical composition but different structure

Question 9

What is Homovalency and Coupled charges?

Answer 9

Homovalent- Same charges on both sides eg
Mg2+=Fe2+

Coupled- Same charges but in different quantities eg
Mg2+ + Ca2+= Al3+ + Na+

Question 10

What are garnets?

Answer 10

Minerals commonly found in metamorphic rocks and colours reflect chemical composition

Question 11

What are sorosilicates?

Answer 11

A silicate mineral sharing one apical oxygen commonly found in the Earths crust eg Epidote and pumpellyite.

Question 12

What are single chain silicates?

Answer 12

Silicate minerals that join to form a single chain.
Minerals include Enstatite and Diopside (pyroxenes).

Question 13

What are sheet silicates?

Answer 13

Silicate minerals that form a sheet like structure.
Minerals include Micas, Muscovites and Biotite.

Question 14

What are double chain silicates?

Answer 14

Silicate minerals that form 2 conjoined chains.
Minerals include Glaucophane, Actinolite and Hornblende.

Question 15

What are framework silicate?

Answer 15

Silicate minerals that form a stable crystal lattice.
Minerals such as Quartz are framework silicates.

Question 16

What are the 2 types of feldspars?

Answer 16

Plagioclase(triclinic)- complete solid solution between Na and K end members eg Anorthite(CaAl2Si2O8) and Albite(NaAlSi3O8)

Alkali(monoclinic)-limited solid solution between Na and K end members eg Albite and Orthoclase/K feldspars eg microcline(KAlSi3O8)

Question 17

What are the 2 types of oxide ore minerals?

Answer 17

Cubic - MgAl2O4(spinel) and FeFe2O4(magnetite)
Trigonal - Fe2O3(hematite) and Al2O3(corundum)

Question 18

What are the 2 sulphide ore minerals?

Answer 18

Cubic 1 - PbS (galena)
Cubic 2 - FeS2 (pyrite)

Question 19

What are the 4 types of carbonate minerals?

Answer 19

CaCO3 - calcite and aragonite
CaMg(CO3)2 - Dolomite
FeCO3 - siderite
Cu2CO3(OH)2 - malachite

Question 20

What determines the mineralogy of a rock?

Answer 20

-Pressure/Temperature
-The chemical composition of the system
-Kinetic barriers to equilibrium

Question 21

Why is Olivine unstable nearer the Earths surface?

Answer 21

Because it breaks down easily and also reacts with quartz to form a new mineral.

Question 22

What are the controlling factors for stability?

Answer 22

Chemical thermodynamics - the energetically of chemical reactions

Kinetics - the rate at which chemical reactions take place

Question 23

What are bedding planes and contacts?

Answer 23

Bedding planes - separate distinct sedimentary layers in a sequence of beds

Contact- any boundary that separates one rock from another

Question 24

What is deposition and emplacement?

Answer 24

Deposition - the laying down of sediment carried by a fluid or gravity flow

Emplacement - the intrusion or eruption of igneous rock which may also form layers

Question 25

What re the 4 stratigraphic principles?

Answer 25

Original horizontality - sediment layers are originally deposited horizontally Superposition - oldest rocks are at the bottom and youngest at the top Lateral continuity - sedimentary layers are laterally continuous over long distances and they don’t terminate abruptly unless eroded, deformed or thinned Crosscutting relationships - any geological feature that cuts across existing rock is younger than the rock it cuts across.

Question 26

What is dip and strike?

Answer 26

Dip - steepest angle between a tilted bed and a horizontal plane Strike - the compass direction of the intersection between a bed and a horizontal plane

Question 27

What are the 3 types of sedimentary rocks and their comprise of minerals?

Answer 27

Clastic - rocks made from pre-existing rocks( sandstones and mudstones) Carbonate rocks - often consists of fragments of carbonate fossils but can be produced from precipitation of carbonates from water eg limestone Chemical sediments - Evaporites, carbonates and FeM oxyhydroxides eg salt, gypsum and Dolomite Minerals eg quartz, feldspars, micas carbonates evaporites and clays

Question 28

What are the 2 types of metamorphism and what increase the grade of metamorphism?

Answer 28

Regional - rocks produced by burial associated with tectonic processes and pressure/temperature varies Contact - rocks produced by heating around igneous intrusions usually at low pressures Deformation of the rock during metamorphism causes the alignment of interlocking minerals and the grain size increase increasing the grade of metamorphism.

Question 29

What minerals are usually found in metamorphic rocks?

Answer 29

Garnets,Micas, Feldspars, quartz, pyroxenes and amphiboles

Question 30

What are the 2 types of igneous rocks?

Answer 30

Intrusive - rocks formed from magma that has not reached the surface and cools slowly underground Extrusive - rocks formed from magma that has erupted on the Earths surface and cools relatively quickly

Question 31

What is a grain, matrix and clast?

Answer 31

Grain : fragments of minerals Matrix : fine-grained material holding everything together Clast : fragments of rocks

Question 32

What is a porphyroblast, porphyroclast and foliation?

Answer 32

Porphyroblast - new mineral grown through reaction Porphyroclast - pre-existing mineral Foliation - alignment of minerals

Question 33

What is ground mass?

Answer 33

Fine grained material, usually glass and fine grained crystals.

Question 34

What are the 7 crystal systems?

Answer 34

-Cubic -Tetragonal -Hexagonal -Trigonal -Orthorhombic -Monoclinic -Triclinic