geology-1.1 minerals

Lustre

the way a mineral reflects light.

Colour

many minerals are white, grey, or colourless. This property is only useful to identify minerals with a distinct colour (augite, olivine, garnet, galena, haematite).

Streak

the colour of a mineral's powder obtained by scraping a specimen across an unglazed porcelain tile.

Cleavage

when minerals break up into regular flat-sided pieces. This happens due to planes of weakness running through the mineral's atomic structure.

Hardness

measured using Mohs Scale and requires the use of a fingernail, copper coin and a steel nail or pin to determine relative hardness.

Acid reaction

0.5 mol dm hydrochloric acid is used to identify calcite. It fizzes and gives off carbon dioxide.

What are the different ways minerals are formed?

1 crystallisation from a melt

2 metamorphic recrystallisation

3 crystallisation from solution in evaporating water

4 crystallisation as cement from flowing pore water

5 crystallisation from hydrothermal fluids

SHREC

S-solidification from a melt

H-hydrothermal activity when hot fluids dissolve minerals and re-deposit them in a more concentrated from in veins and faults.

R-recrystallisation from metamorphism

E-evaporation of sea water

C-cementation is the precipitation and crystallisation of quarts from flowing pore waters in loose sediments to cement them into solids.

Hydrothermal activity

when hot fluids dissolve minerals and re-deposit them in a more concentrated form in veins and faults.

Scanning Electron Microscope (SEM)

is a microscope in which the surface of a specimen is scanned by a beam of electrons that are reflected to form an image. Produces images up to a magnification of X1,000,000.

Electron Microprobes

bombard mineral samples with an electron beam, emitting x-rays at wavelengths characteristic to the elements being analysed.

what are scanning electron microscope and electron micropobe used for?

to image mineral samples