Lecture 7

Question 1

What are minerals?

Answer 1

Any naturally formed chemical substance having a definite chemical composition (but not fixed) and a characteristic crystal structure. (not all follow this exact definition)

Question 2

What place has the highest mineral diversity on earth?

Answer 2

The crust

Question 3

How many mineral types and varieties are there on earth?

Answer 3

4000 types, 10 000 varieties.

Question 4

What percentage of impurities will minerals accept (max) before changing?

Answer 4

40% (some will change after 1%)

Question 5

What can minerals not do?

Answer 5

Break into different mineral substances (ex: if you hit a block of table salt, it won’t break into Na and Cl)

Question 6

What are mineraloids and an example?

Answer 6

Substances with a definite chemical formula, but are amorphous (ions not arranged properly) NO CRYSTAL STRUCTURE-opal is an example (precipitation of silica forms an array of colours)

Question 7

What are organic minerals?

Answer 7

Minerals that require the action of certain organisms to form (ex: Whewellite requires precipitation of bacteria).

Question 8

What is the difference between organic sulphur and inorganic?

Answer 8

Inorganic- small crystals

Organic- Produced by bacteria, creates wide crystals

Question 9

Who was the first to classify minerals and how did he classify them?

Answer 9

Aristotle- Classified by colour, shape, weight, taste

Question 10

What are some examples of mineral imperfections?

Answer 10

Azurite-presents intergrowth (shared portions of crystal structure)
Tourmaline- in pure state, lacks colour. However, has some coloured areas created by different ions.

Question 11

Who invented the microscope and what did he discover?

Answer 11

Anthony Van something from the Netherlands. 1st discovery of cells

Question 12

How was the microscope transformed in the Early 90s?

Answer 12

Developed technology to increase the magnification of microscope to see crystal structure. Beam of electrons, and whatever is reflected back is observed

Question 13

How did the mineral Galena present under the microscope?

Answer 13

Repeating patters of light and dark coloured spots. Light=lead. Dark=sulphur. First direct observation of crystal structure in 1991.

Question 14

What shape will never be formed with geometrical packing?

Answer 14

Rounded shapes. Has to have a face and sides

Question 15

What are crystals?

Answer 15

Fundamental units of matter organization which have regular, repeating architecture (unit cell) reflecting packing of atoms

Question 16

What are some of the ideal geometrical packing shapes?

Answer 16

Tetrahedron, Cubical (1), Octaedron, Cubical (2)

Question 17

What is the crystal structure of diamond?

Answer 17

Carbon atoms situated in corners of tetrahedron-only creates covalent bonds (toughest in nature). Crystal structure is homogenous.

Question 18

How are diamonds formed?

Answer 18

High pressures-only form in upper mantle. Volcanic eruptions that raise molten matter to the surface can create diamonds on the surface.

Question 19

What is graphite’s crystal structure?

Answer 19

Unit cells of carbon atoms form a hexagon (not homogenous), covalent (plains) AND ionic bonds (between plains). Weak element parallel to plain.

Question 20

How is graphite formed?

Answer 20

Thermomaturation of dead organic animals-die at bottom of basin, burial process happens and trace elements are expelled (sulphur, phosphorous, nitrogen, oxygen , carbon).