Week 1 - Intro Flashcards
What is a rock?
A solid aggregate of one or minerals that are formed through geological processes. They are classified into sedimentary, igneous and metamorphic based on their formation processes.
What is a mineral?
A mineral is a naturally occurring, solid substance with a specific chemical composition and an ordered atomic arrangement.
What properties are needed for something to be a mineral?
- Naturally forming
- Solid
- Formed by geological processes
- Definable chemical composition
-Crystalline structure
-Inorganic
How can minerals be classified?
Rock forming minerals - Primary constituents of igneous, metamorphic and sedimentary rocks
Industrial minerals - Minerals that are mined for their economic value
Ore minerals: Minerals that contain one or more valuable elements that can be extracted for profit.
What is a crystal?
Describes a mineral, which refers to a single continuous piece of crystalline solid that is characterized by distinct flat surfaces known as crystal faces.
What are the three atomic bonds in minerals and how do they work?
Covalent bonds: Atoms share electrons. This type of bond tends to be strong
Ionic bonding: Atoms transfer electrons, leading to the formation of oppositely charged ions that attract eachother
Metallic bonding: Involves a delocalization of electrons that allows them to move freely among many atoms, resulting in electrical conductivity.
What does the bonding type influence in a mineral?
Ionic: Strong bonds, moderate/high hardness, soluble, symmetry, poor conductor
Covalent: Very strong and hard, low solubility, highly directional and lower symmetry, insulator
Metallic: Moderate strength, soft ductile and malleable, insoluble, very high symmetry and a good conductor.
What are all the properties we use to describe minerals?
Colour
Streak
Lustre
Hardness
Specific gravity
Crystal habit
Cleavages and fractures
Optical properties
Advanced methods (such as x-ray diffraction, electron microprobe analysis)
Why does colour differ in minerals?
Results from how the mineral reacts with light.
What are idiochromatic minerals?
Tend to have a constant colour such as malachite being green
What are allochromatic minerals?
Will have different colours due to impurities in the atomic structure or deformation of the crystal lattice.
What are Pseudoachromatic minerals?
Shows false colour due to optical effects. May have different layers that react differently.
How does streak help identify a mineral?
Shows the colour of the mineral when powdered which is more consistent between minerals that may be allochromatic. Will always be the same for a mineral.
What does lustre mean when identifying minerals?
Refers to the way light scatters off the surface of the mineral.
How does hardness and toughness differ?
Hardness is measured by is resistance to scratching assumed by Mohs hardness scale. It is a surface feature. Toughness is an internal feature.
For example, diamonds are hard so you cant scratch them but are not as tough as they have cleavage so can break.
What does specific gravity mean in a mineral?
Measures the density of a mineral relative to the density of water.
What does crystal habit mean when identifying minerals?
The general appearance of crystals, which determines the shape and arrangement of the minerals crystals. Some minerals are blocky other are slender, shows at what rate the crystal grew.
What does cleavage mean?
Cleavage refers to the tendency of a mineral to break along specific planes of weakness.
What is a fracture in a mineral?
Indicates a random break in the rock, all minerals can fracture but not all minerals will have cleavage.
What are the 7 types of minerals?
Silicates
Carbonates
Sulfates
Phosphates
Oxides
Halides
Sulfides
Native elements
How do you layout a mineral description page?
Sample No
Sketch
Description
- Colour
- Streak
- Lustre
- Hardness
- Specific gravity
- Crystal habit
- Cleavages and fractures
