Week 1: Minerals info Flashcards
What is the definition of a mineral?
(5 criteria)
1: Naturally occurring.
2: Inorganic (no H-C bond).
3: Solid.
4: Specific chemical composition.
5: Ordered atomic structure.
What is a solid solution series?
The compositional range in minerals that experience substitution in 1 or more atomic sites.
Ions with the same charge and similar size can substitute for one another.
Provide an example of minerals that show solid solution series.
Olivine. Mg rich end and an Fe rich end. End-member mineral composition, entirely one element.
How are minerals classified?
According to their dominant anion.
Describe the silicon-oxygen tetrahedron molecule.
One silicon (Si) atom covalently bonded to four oxygen (O) atoms, forming a tetrahedral shape. This structure has a SiO₄⁴⁻ charge.
State what the 7 different silicate groups are.
[ Ring Frodo since double, silvery necromancers ARE succumbing. ]
—(Tetrahedron covalently share O)—
Ring Silicates
Framework Silicates
Single chain Silicates
Double chain Silicates
Sheet Silicates
—(Single tetrahedron)—
Nesosilicates
Sorosilicates
What is a crystal?
It refers to any natural solid with an ordered, repetitive, atomic structure.
A single, continuous piece of a crystalline solid bounded by flat crystal faces.
What are Isotopes?
Atoms with the same atomic number but different mass number. (Same protons but varying neutrons.)
What is an ion?
Atom with either a positive or negative charge. (Lost or gained electrons.)
When does an atom donate electrons and when does it receive electrons?
Less than 4 it donates.
More than 4 it shares/accepts.
What is the difference between ionic and covalent bonding?
Ionic bonding is the transfer of electrons.
Covalent bonding is the sharing of electrons between two atoms.
What is a polymorph?
Two minerals with the same chemical composition but a different crystal structure. Due to differences in temperature and pressure.
What is an example of a polymorph?
Carbon Polymorph.
- Graphite (low T & P)
- Diamond (extremely high T & P)
Why are crystals rare?
They form the crystal faces best in open cavities.
Why is crystal shape a valuable tool in mineral identification?
A mineral always has crystal faces at a diagnostic angle. ( Always the same.)
What are the five ways a crystal can grow?
1: SOLIDIFICATION OF A SMELT.
- The freezing of a liquid to form a solid. Atoms accumulate on a central seed. [ice]
2: PRECIPITATION FROM A SOLUTION.
- Atoms/molecules/ions dissolved in water bond together and separate out. Or also precipitate from slowly moving groundwater. [geode]
3: SOLID STATE DIFFUSION.
- The movement of atoms/ions through a solid into a new crystal structure. Very slow process. [garnets]
4: BIOMINERALIZATION.
- When living organisms cause minerals to precipitate either on or within their bodies. [clams]
5: GAS PRECIPITATION.
- When volcanic gas/steam enters the atmosphere and cools abruptly.
How does a geode form?
Precipitation from slowly moving groundwater which fills a spherical shaped hollow within a rock. Forms inward projecting crystals.
What is the morphology of crystals?
The external shape and form of a crystal reflects the arrangement of its internal crystal lattice. (Symmetry and Geometry)
What is an amorphous structure?
A solid where atoms are not arranged in a definite crystal structure. [glass]
What are the diagnostic characteristics of minerals?
- Colour.
- Streak.
- Lustre - metallic/non-metallic.
- Hardness - resistance to scratching.
- Cleavage/Fracture.
- Density (S.G.) - the ratio of the weight of a mineral to an equal volume of water.
- Reaction to a dilute HCl.
- Magnetic. (magnetite)
- Habit of a crystal form - Characteristic shape.
- Double refraction (calcite)
- Fluorescent in UV light.
- Radioactive (Uraninite)
- Twinning
What is the difference between cleavage and fracture?
And give examples.
Cleavage is the tendency to break along reflective planar surfaces. [Muscovite]
Fracture is very random breaks. [Quartz]
How do minerals break?
The break depends on the molecular bonds between atoms.
If there are planes of weakness the mineral will display cleavage. If there are equal molecular bonds in all directions the mineral will fracture.
What are some different cleavage directions?
1 (Flat sheets)
2 at 90* (2 rectangles)
2 not at 90* (2 Parallelogram)
3 at 90* (Cube)
3 not at 90* (Rhombohedron)
4 (Octahedron)
6
What are the 10 main classes of minerals?
[ So, Hilariously oxen have colourful notes, super pricey, naturally selling.]
1: Silicates (2 - 10 are non-silicates)
2: Halides
3: Oxides
4: Hydroxides
5: Carbonates
6: Nitrates
7: Sulphates
8: Phosphates
9: Native elements
10: Sulfides
What are ferromagnesian silicates? Give examples.
Silicates with Fe and/or Mg in their structure. Most are dark-coloured and denser than non-ferromagnesian silicates. [Olivine]
What is important to know about silicates?
Most nb mineral group as they make up most of the rock forming minerals.
Very abundant (lots of Si and O)
Basic building block is the silicon-oxygen tetrahedron molecule. ( - charge)
There are 7 groups which form based on how the tetrahedron links together.
What are nesosilicates?
Isolated Si-O tetrahedron.
Explain the classification of the Feldspar group of minerals.
The Feldspar group is a 3 end-member of a solid solution series.
End members: K-feldspar, Albite & Anorthite.
Alkali feldspar are the solid solutions between end members K-feldspar and albite.
Plagioclase feldspar are the solid solutions between albite and anorthite.
Limited solid solutions occur between the other two end members.
When do Alkali feldspar and Plagioclase feldspar form?
Alkali form from 500 to 1100 degrees Celsius. [lower T]
Plagioclase form from 1100 to 1544 degrees Celsius. [higher T]
