Week 1 and 2 Flashcards
What is a Unit Cell?
The smallest unit which, when repeated in 3D will build the crystal structure.
What are the 3 types of Unit Cell?
Simple Cubic, Body-centred Cubic and Face-centred Cubic
What is twinning?
Two separate crystals are inter grown and share some common points in the crystal lattice.
What are the 4 types of twinning?
Rotational, Simple, Multiple(lamellar) and Cyclic.
What is cleavage?
Where atoms are located at regular positions within the crystal lattice. Minerals can have single(sheet silicates) or multiple(pyroxenes and amphiboles) planes of cleavage.
What are mafic minerals?
Dark coloured minerals rich in Magnesium and Iron.
Eg Olivine, Pyroxenes, Amphiboles and Biotite.
What are Felsic minerals?
Light coloured minerals rich in Silicon and Aluminium. Eg Quartz, Feldspars and Muscovite.
What are isomorphic and polymorphic minerals?
Isomorphic- Different chemical composition but similar structure
Polymorphic- Same chemical composition but different structure
What is Homovalency and Coupled charges?
Homovalent- Same charges on both sides eg
Mg2+=Fe2+
Coupled- Same charges but in different quantities eg
Mg2+ + Ca2+= Al3+ + Na+
What are garnets?
Minerals commonly found in metamorphic rocks and colours reflect chemical composition
What are sorosilicates?
A silicate mineral sharing one apical oxygen commonly found in the Earths crust eg Epidote and pumpellyite.
What are single chain silicates?
Silicate minerals that join to form a single chain.
Minerals include Enstatite and Diopside (pyroxenes).
What are sheet silicates?
Silicate minerals that form a sheet like structure.
Minerals include Micas, Muscovites and Biotite.
What are double chain silicates?
Silicate minerals that form 2 conjoined chains.
Minerals include Glaucophane, Actinolite and Hornblende.
What are framework silicate?
Silicate minerals that form a stable crystal lattice.
Minerals such as Quartz are framework silicates.