Minerals Flashcards
1
Q
5 requirements of a mineral
A
- Solid
- Naturally occurring
- Fixed chemical composition
- Crystalline structure
- Inorganic
ex. quartz, ice
2
Q
mineraloids
A
- Similar to a mineral but no ordered arrangement of atoms
- Because of the lack of ordered atoms, is amorphous rather than crystalline
- Ex. Opal
3
Q
rocks
A
Aggregates of minerals (ex. Granite – made up of quartz, feldspars and biotite mica)
4
Q
atomic structures
A
- Protons, electrons, neutrons -> atoms -> elements -> minerals
- Element: form of matter that can’t be broken down into a simpler form
- Atom: smallest subdivision of matter that retains chemical properties of an element
5
Q
bonds
A
- attachments between atoms in a crystalline structure.
- Important because different bonds lead to different physical properties which can be used to identify minerals
- types of bonds: covalent, ionic, metallic, van der waals
6
Q
covalent, ionic, metallic, and van der waal bonds
A
- Covalent: ions shared, makes strong bonds (ie. Diamond)
- Ionic: ions given away
- Metallic: Weak covalent bond occuring in metallic elements, outer electons travel freely between adjacent atoms
- Van der Waals: weak bonds between slightly polarized atoms
7
Q
ions
A
- Atom that has positive or negative net charge due to gain or loss of electrons
- Cation = +, anion = -
8
Q
mineral groups
A
- Minerals divide into groups with like physical properties, based on their anionic groups (negatively charged part of mineral)
- Silicates
- Carbonates (important for limestone; ex. calcite, dolomite)
- Ore minerals (ex. galena, pyrite)
- Sulfates
- Sulfides
- Oxides
9
Q
silicates
A
- One third of all minerals -> 90-95% of earth’s crust
- Silica tetrahedron is basic building block of all silicate minerals
- Different arrangements of tetrahedrons lead to different minerals (ex. Isolate tetrahedron = olivine, single chain = pyroxene, double chain = amphibole, sheet structure = micas and clays, 3d framework = quartz and feldspar)
- Dark silicates (ferromagnesian) and light silicates (felsic)
10
Q
dark vs. light silicates
A
- Dark silicates = ferromagnesian
- High Mg, Fe content
- In oceanic crust
- Ex. Pyroxene, amphibole
- Light silicates = felsic
- Lack Fe
- Ex. Quartz, feldspar
11
Q
mineral composition of earth’s layers
A
- Crust
- Dominated by oxygen and silicates (94%)
- Minerals: fedspar, quartz - Mantle
- Heavier, denser
- Oxygen, silica, iron, and magnesium
- Minerals: Olivines, pyroxine - Core
- Probably composed of nickel and iron
- No direct samples (educated guess from geophysical evidence)
12
Q
identifying minerals using physical properties
A
- Each one has unique set of physical properties, such as:
- Hardness
- Cleavage
- Fracture
- Crystal form
- Streak and lustre
- Colour
- Taste
- Specific gravity
- Magnetism
- Reaction with acid
13
Q
hardness
A
- what scratches what?
- Mohs’ hardness scale
- 1 = weakest, 10 = strongest
- Weaker minerals can be scratched by stronger minerals
14
Q
cleavage
A
- ability for mineral to split along planes of weakness
- Quality: how smooth the faces are – perfect, imperfect, distinct, good, fair, poor
- Difficulty: how easily the cleavage breaks – easy, hard, difficult
- Weak bonds between layers and strong bonds within layers make it easy to splot (ie. Mica – perfect cleavage)
- With 2 or more cleavages, the angle between them can also help identify (ie. Feldspar is 90 degrees, amphibole isn’t)
15
Q
fracture
A
- tendency to break along an irregular surface not controlled by cleavage
- ex. Conchoidal fracture (curved, spiral/conch-shell-like fracture)
- Quartz often displays this
