rocks and minerals

Question 1

Whats is GIS

Answer 1

• geogrpahic information systems
• store, analyze, and visulaize data for geographic positions on Earth’s surface
• a computer-based tool that examines spatial relationships, patterns, and trends in geogrpahy

Question 2

what is a mineral

Answer 2

• a naturally occuring, soild inorganic substance with a specific chemical composition
• often forms in crystal lattice
• ex. quarts, ice

Question 3

what is a rock

Answer 3

• and aggregate of minerals or non-minerals without a specific chemical composition
• no specific chemical formula
• classified based on certain parameters
• ex. schist with visible garnet crystals

Question 4

general mineral info

Answer 4

• most important rock-forming minerals contain silicon and oxygen. this forms silicates
• 90% of minerals in Earth’s crust fall in 5 groups of silicates:
• quarts- silica
• feldspars
• pyroxene- Fe, Mg
• mica
• clay minerals (kaoliinite, montmorillonite)
• non-cilicate minerals: common on Earth’s surface; calcite and colomite
• ore minerals: magnetite, hematite, galena, sphalerite

Question 5

how do we identify minerals

Answer 5

• colour
• streak
• luster
• harness (scratchability)
• cleavage
• fracture
• specific gravity
• magnetism

Question 6

colour identifiication

Answer 6

• most noticeable
• least accurate

Question 7

streak

Answer 7

• colour when mineral ground to a fine powder
• silicate minerals do no streak because they are stronger than the ceramic plate
• hematite streaks red/brown

Question 8

luster

Answer 8

• reflection of light from mineral surface
• metallic
• or non-metallic
• ex. galena, spharelie, talc

Question 9

hardness

Answer 9

• moh-harness scale (1-10)
• talc (very soft)- 1
• diamond- 10
• fingernail, copper penny, knife/glass plate, steel nail, masonary drill bit

Question 10

cleavage

Answer 10

• ability of a mineral to break along preferred directions when struck

Question 11

fracture

Answer 11

• surface along which a mineral breaks; not controlled by cleavage
• cannot have both fracture and cleavage, one or the other

Question 12

specific gravity

Answer 12

• way to express density
• ratio of density of mineral to water
• water p=1
• magnetite has a specific gravity value of 5.2, meaning 1cm3 of magnetite will be 5.2 times as heavy as 1cm3 of water

Question 13

magnetism

Answer 13

• some minerals are magnetic others are not

Question 14

rock cycle

Answer 14

• change from one type to another with time
• KNOW DIAGRAM FOR EXAM IT WILL BE ON THERE

Question 15

what is an igneous rock

Answer 15

• also called volcanic rocks
• form from solidified magma
• either at the Earth’s surface (extrusive) or underground/below Earth’s surface (intrustive)

Question 16

ways igneous rocks are classified

Answer 16

• Texture
• mineralogy

Question 17

texture for igneous rocks

Answer 17

• coarse grained igneous rocks cooled slowly beneath Earth’s surface allowing large crystals to form
• these rocks are INTRUSIVE and are called phaneritic
• can you see individual grains?
• fine grained igneous rocks cooled quickly on the Earth’s surface so large crystals did not have time to form
• these rocks are EXTRUSIVE and are called aphanitic

Question 18

mineralogy

Answer 18

• colour of the rock often reflects the composition of the rock
• felsic rocks are light in colour, have high silica content and contain light-coloured minerals
• mafic rocks are dark in colour, have low silica content and contain dark-coloured minerals

Question 19

sedimentary rocks

Answer 19

• form from sediment grains transported by water, ice, or air
• compacted, cemented- lithified
• clastic rocks (form from pre exisiting rocks from erosion and weathering)
• ex. conglomerate, sandstrone, shale (mudstone)
• clasts and matrix: clastic sedimentary rocks are made up of cemented particles (clasts or grains)
• often with matrix (finer-grained maerial) between the large grains
• chemical precipitates of bioclastic debris ex. limestone- fossil fragments, evaporites- halite

Question 20

grain size sedientary rocks

Answer 20

• described using the udden-wentworth scale
• use a grain size card when looking at hand samples

Question 21

grain size distribution

Answer 21

• sorting: organization according to grain size
• well sorted (same size)
• poorly sorted (variable sizes)
• can tell us distance from source (poorly indicates closer to sedimentary source)

Question 22

grain shape

Answer 22

• very angular to well rounded
• angular means closer to source

Question 23

metamorphic rocks

Answer 23

-metamorphism refers to changes to rocks that take place in the Earth’s interior
- the changes may be new textures, new mineral assemblages or both
- the new rocks is a metamorphic rocks
shale to slate to phyllie to schist to gneiss
sandsone to quartzite
limestone to marble
basalt to hornfels

Question 24

texture for metamorphic rocks

Answer 24

• how minerals are alinged or bonded
• how they are oriented
• different than from sedimentary
• foliated: minerlas are alligned
• foliation is caused by differential stress which deforms objects into flattened forms

Question 25

types of foliation

Answer 25

• slaty: nearly perfect, planar foliation with fine (mircoscopic) grains
• phyllitic: parallel, wavy foliation with a shiny/glossy lustre, fine grains
• schistose: parallel and subparallel foliation, medium to coarse grains
• gneissic: alternating light and dark layers, medium to coarse grains
• non foliated metamorphic rocks: rock name on basis of composition. ex. marble or quartzite

Question 26

rock vs mineral

Answer 26

• a rock is naturally formed, consolidated material composed of grains of one or more minerals
• a mineral is a naturally occuring, inorganic, crystalline solid that has a definite chemical composition