Rock Determination HydroGeo

Question 1

The three types of rocks

Answer 1

igneous, metamorphic, sedimentary

Question 2

What are the two types of igneous rocks and how were they formed?

Answer 2

intrusive - formed in earth, solidified slowly, small minerals
extrusive - cooled quickly outside the earth, coarser minerals

Question 3

What is the basic silica structure?

Answer 3

SiO4 - this has a charge of -8 and is often compensated by Fe or Mg. This is known as the olivine group

Question 4

What is the pyroxene group?

Answer 4

one line of SiO4 minerals

Question 5

What is the amphibole group

Answer 5

a layer of double structures

Question 6

What are phyllosilicates?

Answer 6

platy minerals

Question 7

What is the tectosilicate group?

Answer 7

a 3D structure

Question 8

What are felsic igneous rocks?

Answer 8

extrusive rocks formed from explosive volcanoes - higher SiO2

Question 9

What are mafic igneous rocks?

Answer 9

Extrusive rocks formed from fluid volcanoes - lower SiO2

Question 10

When does weathering occur more quickly with rocks?

Answer 10

When there are more metals - these are easier to weather than chemical bonds - van der Waals forces are easier to break than chemical bonding

Question 11

Granite

Answer 11

intrusive igneous rock. Lightly coloured with a mix of light and dark silicates. Mainly light minerals. The darker minerals weather first. Same chemical composition as rhyollite. Weathers slower than rhyollite, unless fractured

Question 12

Diorite

Answer 12

Intrusive Igneous Rock. 50/50 distribution of light and dark silicates. Doesn’t weather fast. Same chemical composition as Andesite

Question 13

Gabbro

Answer 13

Intrusive igneous rock. Predominantly large dark minerals. Same chemical comp. as basalt , but weathers slower (larger minerals) unless fractured.

Question 14

Rhyolite

Answer 14

light extrusive igneous rock. Small minerals, high viscosity when forming. Rare, so usually solidifies inside the earth. Weathers faster than granite –> smaller minerals

Question 15

Andesite

Answer 15

50/50 extrusive igneous rock. Has more dark minerals than rhyolite. Twins with diorite

Question 16

Basalt

Answer 16

dark extrusive igneous rock. Lots of metal ions. Rock forms in polygones during cooling and solidification process. The scrambled egg on top has higher porosity, volcanic gas causes bubbles.

Question 17

Tuff

Answer 17

volcanic ash and lava bombs fall back on the earth. When it cools in the air, aquifer, when it cools on the surface, aquitard.

Question 18

Two types of diagenesis

Answer 18

reduction of volume (compression/compaction at large depth), mineralogical change (chemical processes between core and water minerals)

Question 19

eg. consolidated coarse clastic sediment

Answer 19

conglomerate

Question 20

eg. consolidated moderately coarse clastic sediment

Answer 20

sandstone

Question 21

eg. consolidated fine clastic sediment

Answer 21

siltstone, shale

Question 22

arenite

Answer 22

consolidated rocks constructed from sand size particles.

Question 23

lutite

Answer 23

consolidated rocks with smaller than sand size grains

Question 24

rudite

Answer 24

consolidated rocks with larger than sand size grains

Question 25

organic vs. clastic limestone

Answer 25

organic - chalk skeletons of algae, sea shells and organisms, clastic is from transported skeleton gragments or from calcite crystals.

Question 26

slate

Answer 26

fine grained rock, developed from clayk strong cleavage preference in one direction.

Question 27

Phyllite

Answer 27

slightly coarser rock than slate with silvery or greenish lustre, minerals not visable, developed from low graded metamorphosed clay

Question 28

Schist

Answer 28

coarse grained rock with parallel structures and clearly visible micas.

Question 29

Gneiss

Answer 29

coarse grained with clearly visible parallel structures of micas and fedspars, characterized by coarse layering. High grade metamorphose. no porosity or conductivity

Question 30

Granite to sand (types of sand)

Answer 30

monocyclic sand - darkest minerals weather fter - weaker van der Waals forces.
polycyclic sand - multiple cycles of weathering - even fewer darker minerals.

Question 31

sand to sandstone

Answer 31

poorly consolidated - still has porosity- to highly consolidated (no pores). high pressure and temp required. sandstone weathers faster than rain.
you can still see sand in sandstone

Question 32

quartzite to magma

Answer 32

make it hotter

Question 33

silt to siltstone

Answer 33

silt –> consolidated siltstone (sedimentary) –>highly consolidated siltstone (metamorphic)

Question 34

gravel to conglomerate to quartzite

Answer 34

gravel –> burial and lithification –> conglomerate –> breccia –> quartzite
Metamorphic -> high temp, pressure, long time.

Question 35

clay to shale

Answer 35

burial and lithification - pushed in same direction

Question 36

shale to phyllite to slate

Answer 36

metamorphic formation, dull colours

Question 37

shale to schist

Answer 37

metamorphic –> colourful.

Question 38

granite to gneiss

Answer 38

metamorphic

Question 39

carbonate sequencing

Answer 39

calcium carbonate –> cretaceous chalk –> carboniferous limestone

Question 40

hardness

Answer 40

on a scale of 10 - silica dominated is roughly 6-7, chalk is 3

Question 41

limestone –> marble

Answer 41

no porosity or hydraulic conductivity anymore, still on chalkboard :)
metamorphic transformation

Question 42

Flintstone

Answer 42

silica skeleton creatures, found in chalk

Question 43

gypsum

Answer 43

calcium sulphate