Lecture 8  OVERVIEW

Details

 

 

Composition space

 

 

Two-component systems (linear composition space)

            FeO Ð SiO2

            Fe2SiO4 Ð Mg2SiO4

 

Three component systems (planar triangle)

                        FeO-MgO-SiO2

                        MgSiO3-FeSiO3-CaSiO3

 

 

Chemical reactions between different mineral phases.  EX:

 

 

 

The minerals that we find together in a given rock are a function of (1) which mineral or combination of minerals is stable, and (2) the bulk composition of the rock.

 

 

One more ternary example: CaO-SiO2-Al2O3

 

 

Mineral

Moles CaO

Moles Al2O3

Moles SiO2

% CaO

% Al2O3

%SiO2

anorthite

1

1

2

25

25

50

grossular

3

1

3

43

14

43

wollastonite

1

 

1

 

 

 

kyanite

 

1

1