Mineralogy Flashcards
Classification of silicates
- Isolated (SiO4) Tetrahedra
- Single Chain of (SiO4) Tetrahedra
- Double Chain of (SiO4) Tetrahedra
- Sheets of (SiO4) Tetrahedra
- Framwork of (SiO4) Tetrahedra
Isolated (SiO4) Tetrahedra
Olivine, Garnet, Kyanite
Which Olivine is more stable at Higher temp
Mg end-member of silicates is more stable than Fe end-members at higher temperature.
what is internal structure of minerals dependent on?
Pressure and temperature supply the energy for structural and chemical changes and their stability.
What is polmorphism?
Minerals of the same composition can have contrasting internal structure that depends on pressure and temp. Phenomenon is known as polymorphism.
Isomorphism
occurence of a group a minerals that have the same crystal structure and similar ionic radii of cations. Alows cation exchange in mineral structure and formation of a solid solution.
What is solid solution?
Different cations appear in the same position of the crystal structure. Solid solution can be described by exchange vectors operating between compositional endmembers.
Is exchange between non-isovalent cations possible?
It is possible but this must be compensated by exchange of another pair of non-isovalent cations. For eks: Albite(NaAlSi3O8) til Anorthite(CaAl2Si2O8).
Hva er en kovalent binding?
Kovalent binding er den sterkeste binding mellom atomer i et mineral hvor to atomer deler på elektronen for å oppnå oktetregelen
Hva er ionebinding i et mineral?
Ionet binding er en måte for atomene å fylle sitt ytterste elektonskallet ved å gi fra seg eller ta i mot et eller flere atomer. Dette type binding er vanlig i Halider.
Forskjellen på ione og kovalent binding mellom atomer i et mineral?
Hovedforskjellen mellom ione og kovalent binding mellom et mineral er at i et ionebinding metallisk og ikke-metalisk atomer gir et atom elekton fra seg til et annet men kovalent binding kun oppstår mellom to lignende atomer dvs. ikke metaller.
what is extinction?
Position in which minerals appear dark between crossed polarizer
What is extinction angle?
The angle between length or a prominent cleavage in a mineral and the position when the mineral is extinct.
What does parallel extinction mean?
If the long direction of the crystal or a prominent cleavage plane is oriented N-S or E-W when the mineral goes extinct.
What does inclined or oblique extinction means?
Mineral has inclined or oblique extinction if it is extinct in the position when the length of the mineral or the cleavage is at some angle to the cross hairs of the ocular.
