L3 introduction to minerals Flashcards
What is a mineral?
A naturally occurring inorganic solid;
with an ordered internal structure;
made up of a regular and repeating arrangement of atoms;
and a definite (but not fixed) chemical composition
Can gemstones be produced by industrial processes?
yes as there are synthetic gemstones
What synthetic gemstones be used for?
Jewellery
Communications
Laser tech
Micro-electronics
Abrasives
How do industrial processes mimic natural processes to produce gemstones artificially?
crystal growth under high temp
(high pressure- synthetic diamonds)
What states are almost all minerals in?
solid (rare exception liquid mercury)
What will the solid structure of minerals look like generally?
regular repeating three-dimensional patterns of atoms, ions or ionic groups
What is the chemical compositions of minerals like?
definite but not fixed
Is the ratio of cations (+) to anions (-) fixed or variable?
fixed
What can make the ratio of cations to anions in minerals more complex?
where different metal cations can substitute into the same structure
Where does crystallisation of minerals occur from?
Magma
What is magma? (not definition but what actually is it as a liquid)
high temperature liquid (high kinetic energy no solid stable)
What happens when magma cools and kinetic energy decreases? (crystallisation from magma)
atoms slow down enough for bonds to persist
Allows nucleation of crystals from melt
What can lead to larger more well formed crystals from magma?
if high temperatures remain, magma
partially molten, atoms still quite
mobile and move toward the surfaces of growing crystals
What happens if there is rapid cooling of magma? (crystal formation)
smaller less well formed crystals
What are pegmatite veins?
found around granites with exotic
minerals hosting rarer elements that don’t fit in “normal” silicate minerals
What are pegmatite veins often targeted for?
mineral exploitation
How can very water rich melts and magma bodies at late stage cooling create large crystals?
low viscosity
leading to very rapid crystal growth rate
What processes are the cause of crystal formation in solid state?
metamorphic
How can minerals form from metamorphic processes?
chemical reactions replacement of of current minerals with new ones
How are atoms transported to sites of new mineral creation? (metamorphic crystal formation)
bonds broken and atoms migrate by solid state diffusion or transported short distances by intergranular fluids
How is the mineralogy of metamorphic rocks more diverse?
includes minerals found in both other rock types plus high pressure / high temperature equivalents
How can minerals form from precipitate?
Precipitation from aqueous solutions containing ions of different sorts
What is solubility?
how much solid material dissolves per unit of solute
What physical conditions can change solubility?
most substances are more soluble in water at higher temperatures and higher pressures
