Lecture 2// Minerals cont. & Continental Drift Hypothesis

Question 1

Seven Major Mineral Classes

Answer 1

1) silicates (Si + O)
2) native elements
3) oxides (O^2-)
4) sulphides (s^2-)
5) sulphates ( [SO^4]^2-)
6) halides ( [F, Cl. Br, I] ^1- )
7) carbonates ( [CO3]^2- )

Question 2

Silicate Minerals (8 common minerals)

Answer 2

• Comprise >95% of the Earth’s crust.
• Of all silicate minerals, feldspar is most abundant.
• Oxygen (45.20%)
• Silicon (28%)
• Aluminum (8%)
• Iron (6%)
• Magnesium (4%)
• Calcium (2.4%)
• Potassium (2.3%)
• Sodium (2.1%)

Question 3

Silica Tetrahedron

Answer 3

• A silica tetrahedron has an overall net charge of 4-, thus it needs to bond with cations to balance the negative charge, or oxygen atoms can bond to other oxygen atoms of nearby silica tetrahedron, sharing the electrons.
• Forms single/double chain, sheets and 3D network.

Question 4

(non)Ferromagnesian silicates

Answer 4

• Subdivided groups of silicates.

- Contains Fe (and usually Mg)

Question 5

Mineral Group

Answer 5

Some minerals within a mineral class are lumped together into a mineral group.
-A set of minerals with similar chemical composition and thus similar physical properties.

-Ex: the feldspar group
All feldspars contain Si3O8, and each variety of feldspar contains varying amounts of Al, Na, Ca, & K.
-They all have a hardness of about 6 and two cleavage directions that meet at nearly 90°.

Question 6

Mineral Species & Mineral Varieties,

Answer 6

• Subgroup within a Mineral Group.
• Mineral groups and species contain individual members termed varieties.

Ex:
-potassium feldspar (aka K-spar); contains K
[varieties: orthoclase (org), microcline (wht), amazonite (grn)]
-plagioclase feldspar (aka plag), contains Na, Ca. or combination of the two
{varieties: albite, labradorite]

Question 7

Exsolution Lamellae

Answer 7

The colour variations/veins in k-spar.

Question 8

Striations

Answer 8

Fine parallel lines on plag.

Question 9

The Scientific Method: Question

Answer 9

Begins with a Question. In order to try and answer that question, facts (data) are collected from observations and/or experiments.

Question 10

The Scientific Method: Hypothesis

Answer 10

• A hypothesis is generated that fits the data and is likely to account for observations in the future as well as at the present.
• It can be tested and critically examined by other scientists (and confirmed, modified, or
  discarded) .

Question 11

The Scientific Method: Theory

Answer 11

• A scientific theory is a hypothesis that survives repeated challenges and is thus supported by vast amounts of favourable evidence.
• They too can be rejected or modified in the face of new empirical findings.

Question 12

The Scientific Method: Scientific Law

Answer 12

• A scientific law does not explain or give a mechanism for a phenomena, it is merely a simple statement based on repeated experimental observations.
• Many are natural laws and some can take mathematical forms, such as Newton’s laws of motion.

Question 13

Continental Drift Hypothesis

Answer 13

-Wegener Believed that the continents were once together as a supercontinent named Pangea which started to break apart beginning about 200 million years ago

Question 14

Alfred Wegener’s Evidence for CDH

Answer 14

1) The obvious fit of the continents. Particularly South America & Africa (matches even better if you match them up at the edge of the continental shelf).
2) Similar mountain ranges and rocks align when Pangea is reassembled (eg. Caledonians in EU, Greenland and NA; Appalachians in NA and Africa).
3) Fossils of the same terrestrial organisms on the now widely separated southern continents.
eg. Glossopteris (tree in southern continents), Mesosaurus (freshwater reptile in SA and Africa)