Chapter 3: Minerals

Question 1

Euhedral crystals

Answer 1

sharp/well defined crystal faces which form when the crystals have ample room to grow

Question 2

Anhedral crystal

Answer 2

When crystals have less space to grow they form not as sleek/clean crystal faces (a bit more chaotic/cramming)

Question 3

Crystal Habit

Answer 3

characteristic shape/look of the crystal

Question 4

Cleaveage

Answer 4

Weak points in the molecular structure of the mineral
- can have 0 - 4 planes of cleavage

0 planes
- conchoidal/irregular fractures

1 planes
- sheet like

2 planes
- flat/square like fractures

3 planes
- cubic/rhombic shape

4 planes
- octahedron

Question 5

How are minerals classified/organized by scientists?

Answer 5

Chemical composition: silicates v. non-silicates

Question 6

Examples of non-silicates

Answer 6

Native Elements (gold & silver)
Oxides  (Hematite, FeO2)
Hydroxides (Goethite, FeO(OH))
Sulfides (Pyrite, FeS2)
Sulfates (Gypsum, CaSO4 (2H2O))
Carbonate (calcite CaCO3)
Phosphates (apatite, Ca 5 (PO 4 3 (F,Cl, OH))
Halides (Fluorite: CaF 2 , halite: NaCl)

Question 7

Which class of minerals are most abundant at the Earth’s crust?

Answer 7

Silicates

Question 8

How are Silicates formed?

Answer 8

Silicate minerals commonly crystalize from magma (molten rock) and follow a specific sequence known as Bowen’s reaction series

• From a very hot environment to a cooler environment
• First minerals crystalize in the hotter environment, and the last ones crystalize in the cooler environment

Question 9

From hotter to cooler temps, what types of silicates form?

Answer 9

Ultramafic
Mafic
Intermediate
Felsic

Question 10

As the molten rock cools, what is happening to the silicate tetrahedron (the molecular level)?

Answer 10

As rock cools, the silicate tetrahedron can form more bonds and will tend to share more of the oxygen’s to do so

Question 11

What criteria have to be met for something to be named a mineral?

Answer 11

Minerals are:

• Solid
• Naturally Occurring
• Crystalline, meaning they have a repeating crystal structure (which have symmetry)
• Have a define chemical composition
• Minerals are INORGANIC! (not made primarily of carbon/carbon-hydrogen)