Lecture 3: Minerals Flashcards
Why are minerals important?
They are the building blocks for rocks
Provide raw materials for a lot of what we use
A mineral is: (5)
Give an example.
- naturally occurring
- a solid
- non living
- has a definite chemical composition
- has a crystalline interior
ex. ice
Why is bonding in minerals important?
Because it gives specific chemical and physical properties that makes each different mineral unique.
Names of the positive and negative ions
Cations +
Anion -
What is the most important mineral family?
The silicates - most abundant
A basic unit of this is silica (SiO4) - tetrahedron with a (-4) charge
What are the 8 mineral properties?
- Crystal habit
- Lustre
- Colour
- Streak
- Hardness
- Cleavage
- Diaphaneity
- Fracture
What is fracture?
This is for minerals that don’t have a distinct breakage (cleavage).
Diaphaneity
Ability to transmit light
- Transparent - light enters and exits the mineral in an undisturbed fashion (glass)
- Translucent - light enters and exits the mineral, but in a scattered and distorted way
- Opaque - light cannot penetrate the mineral (metal)
Cleavage
The minerals tendency to break along lines of weak bonding.
This breakage reflects the mineral’s patterns of breakage.
Hardness, how is this measured?
Most useful property, measures its resistance to material scratching.
It is measured in units of Mohs.
Streak
The colour of its powdered form. (when scratched along a streak plate)
Colour
The most deceptive property
Lustre
How the mineral reflects light.
Metallic: minerals reflect light like polished metal.
Non metallic: do not reflect light in a metallic way.
Examples of this are vitreous (glassy), pearly, and greasy (oily).
Crystal habit
External geometric shape - its arrangement of atoms
What is an element?
A pure chemical substance that can’t be broken down to other substances, the smallest particle of an element is called an atom.
What is the atomic number?
It is the number of protons that an element has
What is the atomic weight of an element?
It’s the total weight of 1 atom: the number of protons, neutrons and electrons
What is ionic bonding and what does it later lead to? Give an example of a product of ionic bonding.
Ionic bonding is when an element (metal) bonds with another element of opposite charge (non-metal). This type of bonding portrays the transfer of electrons.
These opposite charges form compounds that later form minerals.
Ex. Salt (Halite - this is a mineral)
What is covalent bonding?
When the two atoms share electrons - this leads to weaker bonds
What other types of bondings exist?
Intermolecular bonding - bonds produced by slight charge imbalances (very weak)
Metallic bonding - occurs in pure metals (gold, copper, silver). Electrons constantly migrate among the ions.
Explain how atoms are the building blocks for earth’s geosphere.
Atoms are the building blocks of minerals.
Minerals are the building blocks of rocks.
Rocks are the building blocks of earth’s geosphere.
What are the 5 types of breakage?
- Basal (1 direction)
- Prismatic (2 directions)
- Cubic (3 directions at right angles)
- Rhombohedral (3 directions not at right angles)
- Octahedral (4 directions)
True or false: Weaker bonds results in less breakage.
False.
weaker bonds = more breakage.
Fracture
For minerals that don’t have a distinct cleavage.
This happens to minerals that have stronger bonds.
- Curved or irregular breakage.
