(2) Minerals

Question 1

What is a mohorovicic?

Answer 1

Where the oceanic and the continental crusts meet

Question 2

Plate Tectonics

Answer 2

• Theory that considers the lithosphere as broken into plates that are in motion.
• IMPORTANT: provides framework for understanding many of the world’s dynamic geologic process. Past and present.
• Plates change sizes over millions of years

Question 3

3 types of plate boundaries

Answer 3

Divergent, Convergent, and Transform

Question 4

Divergent Plate Boundaries

Answer 4

• Plates move apart from each other.
• Magma rises from hot asthen to create new crust in the gap between the plates.
• Mechanism of successive separation of plates and filling with magma to produce new oceanic lithospheres

Question 5

Convergent Plate Boundaries

Answer 5

• The plates are moving together.
• The less dense the plates will override the denser plate.
• The denser plate descends into the mantle (subducted).
• Oceanic crust is subducted beneath continental crust.

Question 6

Transform Plate Boundaries

Answer 6

• Plates slide past each other.
• Plates scrape and deform as they pass each other.
• Results in earthquake along the boundary.

Question 7

Minerals, Rocks, Sediment, Soil definition

Answer 7

• M: The basic building blocks of materials that make up the solid part of the earths surface.
• Rocks: a consolidated aggregate of one or more minerals
• Sediment: unconsolidated particles created by weathering and erosion of rocks.
  Soil: an unconsolidated combination of minerals and organic material.

Question 8

Why study minerals?

Answer 8

• Over 4000 known and new minerals are identified each year.
• 25-30 important rock-forming minerals
• Helps to understand the origin of rocks, soils, and sediments.
• Finding and exploiting natural resources.
• Predictive behaviors of materials.

Question 9

What is a mineral?

Answer 9

• A naturally occurring inorganic solid.
• A chemical composition that i fixed or variable within a limited range.
• Uniform and constant chemicals and physical properties
• Has a definite crystal lattice structure.

Question 10

Mineral Groups

Answer 10

• Native elements
• Silicates
• Carbonites : calcite, dolomite
• Oxides: hematite, magnetite, ice
• Sulphites: pyrite, galena, spalertite, cinnibar, chacopyrite
• Sulphates: anhydrite, gypsum, barite
• Halides: halite, sylvite, fluorite

Question 11

Native Elements

Answer 11

Metals (Au, Cu,..), non-metals (C, S,..)

Question 12

Silicates

Answer 12

• Most common rock forming minerals (about 1/3 of all minerals)
• Basic building block is the silicon oxygen tetrahedrum (SiO4)^-4
• Forms the SOT and plus one or more elements
• Arrangement in a crystal lattice depends on : sharing of oxygen atoms ; balance by positive ions

Question 13

Silicate structures (arrangement of SOT and other elements)

Answer 13

• Isolated silicate structures are interconnected by cations
• Single chain structures share two oxygen
• Double chain structures share three oxygen
• Sheet structures share three oxygen and have weaker bonds since it connects as a sheet
• Network structures connect on any side (equidimentional)

Question 14

Mineral characteristics are a function of..

Answer 14

.. Chemical composition AND the way the elements are arranged in a crystal lattice

Question 15

Chemical composition of minerals

Answer 15

• Properties of the elements (size of ions, types of bonds, etc.)
• Some minerals consist of one element
• Most are compounds
• More than 100 elements, but most made up of only 8 (O, Si, Al, Fe, Ca, Na, K, Mg) in different combinations
• These 8 elements make up about 99% of Earth’s crust

Question 16

Mineral Formation

Answer 16

• A tiny early crystal acts as a seed for a future growth
• Atoms migrate to the seed and attach to the outer face
• Growth moves faces outward from the centre
• Unique shape reflects the crystals internal shape
• Many minerals may take different forms (granular, aggregate, fibrous, etc
• BUT all forms of the same mineral will have the same lattice structure at the molecular level
• There are also MINERALOIDS (inorganic solids, but no crystal lattice. Glass, opal)

Question 17

Physical Property: Crystal form

Answer 17

• A crystal is a solid with smooth planar faces whose orientations are determined by the lattice structure
• Angle between faces are consistent for a mineral (Steno’s Law)
• Internal lattices (silicate structures)
• Non-perfect crystals are more common, usually called grains
• Perfect crystals require no interference during growth from other minerals or changing conditions of temperature, pressure, etc.

Question 18

Euhedral

Answer 18

Near- Perfect

Question 19

Anhedal

Answer 19

Irregular

Question 20

Physical Property: Colours (and Streak)

Answer 20

• Can be highly variable due to impurities/slight changes in compositions. Like Corundum
• Streak: colour of fine powder less variable than crystals
• Produced by scraping specimen on unglazed porcelain
• Most streaks are white, but some are distinctive
• Constrained by the hardness of porcelain

Question 21

Physical Property: Luster

Answer 21

• Reflection of light from a surface
• Metallic: gold, copper, etc.
• Non-metallic: glassy, earthy, pearly, silky, etc.

Question 22

Physical Property: Cleavage Breaks

Answer 22

• Directional breakage along planes pf weakness in lattice
• Breaks along smooth planar surfaces (cleavage planes)
• Number of directions : 1 dir = sheets, 2 dir = blocks, 3 dir = cubes, 4-6 uncommon (diamond has 4)

Question 23

Physical Property: Fracture Breaks

Answer 23

When a mineral breaks along an irregular surface

Question 24

Physical Property: Specific Gravity

Answer 24

Mass of substance/mass of equal volume of water

Question 25

Physical Property: 'Play of colours'

Answer 25

Rainbow iridescence due to arrangement of lattice (acts like prism)

Question 26

Physical Property: Striations

Answer 26

Parallel lines on crystal faces due to minute changes in lattice orientation (pyrite)

Question 27

Physical Property: Hardness (test)

Answer 27

- MOH's scale of 'scratchability' a relative hardness scale - 1 softest (scatch with a fingernail) - 3 soft (scratch with penny) - 5 medium (scratch with knife) - 10 hardest (diamond)

Question 28

Physical Property: Double Refraction

Answer 28

Refraction of light entering/leaving mineral creates double image

Question 29

Physical Property: Tarnish

Answer 29

Weathering (usually oxidation) of mineral surface (Cu = green, Au = black)

Question 30

Physical Property: Transparent, Translucent, and Opaque

Answer 30

- Transparent: clear and allows light to pass through - Translucent: less clear but still allows light to pass through - Opaque: light cannot pass through

Question 31

Physical Property: Tenacity

Answer 31

Properties of molecules to resist separation

Question 32

Physical Property: Brittle

Answer 32

Hard but liable to break of shatter easily

Question 33

Physical Property: Malleable

Answer 33

Able to be hammered or pressed permanently out of shape without breaking or cracking

Question 34

Physical Property: Ductile

Answer 34

Able to be drawn into a thin wire

Question 35

Physical Property: Elastic

Answer 35

Able to resume its normal shape spontaneously after contraction or distortion

Question 36

Physical Property: Taste/ smell

Answer 36

- Some minerals have distinctive tastes or smells | - Examples: Copper, Iron. Petroleum

Question 37

Physical Property: Solubility, Radioactivity, and Phosphorescence/Luminescence

Answer 37

- Soluble in acids - Has radioactive traits - Glows or retains light