Ch.3: Minerals

Question 1

Mineral

Answer 1

a naturally-occurring, inorganic crystalline solid that has a definite chemical composition and specific physical properties

Question 2

Crystaline material

Answer 2

a solid having a regular internal atomic

arrangement; may or may not have formed as a crystal

Question 3

Crystal

Answer 3

a solid having external crystal faces that reflect its internal crystalline structure; crystal faces have a precise geometric arrangement

Question 4

Rock

Answer 4

an aggregate of one or more minerals; texture (size and

arrangement of mineral grains) indicates the rock’s origin

Question 5

Igneous Rock

Answer 5

formed from crystallization of molten rock

magma); may be cooled slowly below surface (plutonic/intrusive) or quickly on or near surface (volcanic/extrusive

Question 6

Sedimentary rock

Answer 6

formed generally from the compaction + cementation of eroded particles, or sediment, in the process of “lithification”

Question 7

Metamorphic

Answer 7

formed from the recrystallization of preexisting rock due to elevated temperature and pressure

Question 8

Rock Cycle

Answer 8

magma → crystallization to form igneous rock
→ weathering into sediment → compaction + cementation into sedimentary rock
→ metamorphism into metamorphic rock → melting to form magma (shortcuts
may occur, e.g. metamorphic rock may weather into sediment rather than heat up
enough to melt, etc.)

Question 9

Polymorphic

Answer 9

same composition; different structures; ex) graphite and diamond
The two polymorphs of carbon (diamond and graphite) are the hardest and softest minerals, a result of different types of atomic bonds.

Question 10

Rock Texture

Answer 10

arrangement of mineral grains inside a rock, not how smooth or rough it feels) is how we distinguish one type of rock from another

Question 11

Eurhedral grains

Answer 11

well-formed, crystallized early, with room to grow

Question 12

Anhedral grains

Answer 12

no crystal faces, grew later, filling in spaces

Question 13

Element and Atom

Answer 13

Element: pure substance that cannot be separated into other elements
Atom: smallest part of an element that retains the characteristics of that element

Question 14

Cation vs. Anion

Answer 14

Cation: positively charged ion
Anion: negatively charged ion

Question 15

Mineral physical properties (8)

Answer 15

Luster: appearance in reflected light; metallic vs. nonmetallic
Color & Streak (color in powdered form)
Hardness: resistance to abrasion; how Mohs’ scale is used
Crystal form: described by number and shape of crystal faces
Cleavage: number of cleavage planes and angle between them
Fracture (irregular, conchoidal): Minerals that have no lattice planes of weakness
Specific gravity (related to density)
Special properties: magnetism; effervescence in HCl acid; striations; iridescence;
fluorescence

Question 16

Carat vs. Karat

Answer 16

Carat = Diamont 1-100
Karot = Gold out of 24k

Question 17

Mineral classes based upon the dominant anion:

Answer 17

Silicates SiO2
4- Most rock-forming silicate minerals
Native elements Cu, Au, C Copper, Gold, Graphite, Diamond; most
valuable ore minerals

Question 18

Si to O ratio

Answer 18

Silicate type Unit Si:O Mineral example
Isolated SiO4 1:4 Olivine
Single chain SiO3 1:3 Pyroxene (augite)
Double chain — — Amphibole (hornblende)
Sheet —- — Mica (biotite, muscovite)
Framework SiO2 1:2 Feldspar (plagioclase, K-feldspar)
Quartz

Question 19

Ionic bond

Answer 19

transfer of electrons (IT)

Question 20

Covalent bond

Answer 20

sharing of electron pairs produces harder mineral

Question 21

Geode

Answer 21

cavity within a rock that can be filled with

well-formed crystals that grew from solution

Question 22

Cleavage

Answer 22

Cleavage is the tendency for a mineral to break along
lattice planes with weaker atomic bonds.
Cleavage creates flat surfaces that may occur in steps.
Cleavage can be distinguished from crystal faces because
cleavage planes go all the way through a mineral;
crystal faces are only on external crystal surfaces.

Question 23

Types of cleavage

Answer 23

One direction, or platy
Two directions (or prismatic) at 90°
Two directions (or prismatic) not at 90 °
Three directions at 90 ° or cubic
Three directions not at 90 ° or rhombohedral
Four directions not at 90° or octahedral

Question 24

Diamonds 4 c’s

Answer 24

1) carat weight
2) color
3) clarity
4) cut:
- Brilliance: the reflection of white light from a stone’s
facets
- Dispersion: also called “fire,” the separation of white light
into the spectral hues

Question 25

Silicates

Answer 25

• Isolated (or independent) Tetrahedra share no oxygens–
  they are linked by cations
• Single-chain structures bonded with
  Fe and Mg
• Double chain of silica tetrahedra bonded together; variety of cations
• Sheet Silicates Muscovite Two dimensional sheets of linked tetrahedra Characterized by one direction of perfect cleavage
• Framework Silicates Potassium Feldspar
  All four oxygens in the silica tetrahedra are shared

Question 26

Are all minerals crystals?

Are all crystals minerals?

Answer 26

No not all minerals are crystals

Yes all crystals are minerals