Lecture 6

Question 1

Non silicate minerals

Answer 1

All minerals that do not have SiO4 as their basic building blocks

Question 2

Hematite

Answer 2

• non silicate mineral
• iron oxide
• Fe2O3 (oxidized form of iron)

Question 3

Magnetite

Answer 3

• non silicate mineral
• iron oxide
• Fe3O4
• mixed valence in terms of iron (Fe3+, Fe3+, Fe2+)
• results in magnetism

Question 4

Geothite

Answer 4

• FeOOH
• non silicate mineral
• iron oxide
• Fe3+

Question 5

Calcite

Answer 5

• non silicate mineral
• classified as a carbonate mineral
• CaCO3
• different colours result from impurities

Question 6

Dolomite

Answer 6

• non silicate mineral
• carbonate mineral
• CaMg(CO3)2
• physical properties change

Question 7

Sulfide minerals

Answer 7

Sulphurs and a metal

Question 8

Pyrite

Answer 8

• non silicate mineral
• sulfide mineral
• FeS2
• “fools gold” colour is diagnostic

Question 9

Galena

Answer 9

• non silicate mineral
• sulfide mineral
• PbS
• shiny luster

Question 10

Native elements

Answer 10

• non silicate mineral
• occurs if element itself is relatively stable and can be found in its elemental form (valence of 0)
• Gold, silver, diamond

Question 11

Gypsum

Answer 11

• non silicate mineral
• sulphate
• CaSO4 2H20

Precipitates only in presence of water

Question 12

Apatite

Answer 12

• non silicate mineral
• phosphate
• Ca5(PO4)3(OH, F, Cl)

Question 13

most common properties used in mineral identification

Answer 13

• crystal form and habit
• cleavage and fracture
• luster, colour, and streak
• hardness
• other properties

Used primarily in the field

Question 14

Crystal habit

Answer 14

Crystal shape: reflects internal crystal structure
-constant interfacial angles
-very diagnostic
E.g. quartz (hexagonal), halite (cubic)

Given time and space

• crystals can grow very large
• if space limited, minerals will interlock

Question 15

Cleavage

Answer 15

Tendency for a mineral to break in preferred direction that follow weak atomic bonds

Cleavage surface is not the same as crystal faces

Question 16

Fracture

Answer 16

Not the same as cleavage

Conchoidal fracturing: smooth and curved surface
Hackly fracturing: jagged and pointed surface
Uneven fracturing: irregular, rough surface

Question 17

Colour, luster, and streak

Answer 17

Colour: not diagnostic

luster: metallic versus non metallic minerals

Streak: diagnostic colour produced by rubbing mineral on porcelain plate

Question 18

Hardness

Answer 18

Resistance to scratching

Review chart

Question 19

Other properties

Answer 19

• density (g/cm3) and specific gravity (weight relative to water) e.g. gold, galena
• reaction to acid (calcite reacts with 10% HCl, dolomite does not)
• taste (halite-salt)
• magnetism (magnetite is a natural magnet)

Question 20

Rocks

Answer 20

A rock is a naturally formed, nonliving, coherent aggregate mass of solid matter that constitutes part of a planet, asteroid, moon, or other planetary object. Minerals are the most common building blocks of rocks

Question 21

Three families of rocks

Answer 21

1. Igneous: formed by cooling magma
2. Sedimentary: formed from either chemical precipitation of material or deposition of transported particles
3. Metamorphic: formed from changing rock as a result of either high pressures, high temperatures, or both

Question 22

Best to study rocks using

Answer 22

Polarized light rather than ordinary because you can distinguish different minerals more easily

Question 23

Magmas and igneous rocks

Answer 23

Composition of magma depends on what melts

Igneous rocks:

• intrusive (plutonic)
• extrusive (volcanic)