minComp {GCDkit}R Documentation

Computing chemical compositions from mineral formulae

Description

These functions calculate chemical compositions (in wt.% of oxides) based on mineral's formula(e).

Usage

minComp(n.at,oxides=major)
plComp(An=0)
olComp(Fo=1)
idealMineralCompositions(my.mins=NULL)

Arguments

n.at

numeric: named vector with numbers of individual atoms

oxides

numeric: names of oxides to be returned

An

numeric: anorthite mass proportion(s), 0-1

Fo

numeric: forsterite mass proportion(s), 0-1

my.mins

character: vector with names of desired minerals

Details

The function minComp takes two arguments. The first is a named vector n.at containing numbers of atoms per formula unit, such as that produced by the function formula2vector. The second contains names of the desired oxide names.

NB that trivalent iron in the formula is to be denoted as 'FeIII'.

The functions plComp and olComp are front ends calculating the chemical compositions of plagioclase or olivine for the respective molar proportions of anorthite (An) and forsterite (Fo) end-members (0 to 1).

The function idealMineralCompositions calculates chemical compositions (in wt. % of oxides) of the selected rock-forming minerals. If none are specified upon the function's call, they can be selected from a list (GUI). Their ideal mineral formulae are based on (slightly modified) database of Le Maitre (1982, Appendix 12). This table with alphabetic list of ideal mineral molecules is stored, together with originally calculated molecular weights, in the file
'mineral_formulae.data'.

Value

A numeric matrix with calculated major-element compositions.

Author(s)

Vojtěch Janoušek, vojtech.janousek@geology.cz

References

Le Maitre RW (1982) Numerical Petrology. Developments in Petrology 8. Elsevier, Amsterdam, pp 1-281

See Also

formula2vector

Examples

# Albite
z<-formula2vector("NaAlSi3O8")      # Number of individual atoms pfu
minComp(z,c("SiO2","Al2O3","Na2O")) # chemical composition in wt. %
     
# Magnetite
z<-formula2vector("FeFeIII2O4")
minComp(z) # chemical composition in wt. %
    
# Plagioclase of given An (0-1)
plComp(0.5)
plComp(seq(0,1,0.1))
    
# Olivine of given Fo 0-1
olComp(0.25)
olComp(seq(0,1,0.1))
    
# Andradite
idealMineralCompositions("Andradite")
    
# Cancrinite
idealMineralCompositions("Cancrinite")
    
# Assorted minerals from Le Maitre's database
which.mins<-c("Fluorite","Halite","Magnetite","Quartz","Orthoclase",
    "Albite","Anorthite","Andalusite")
out<-idealMineralCompositions(which.mins)
out<-data.frame(out)
print(out[order(out$SiO2),])    # Sort the output by increasing silica

[Package GCDkit version 6.2.0 Index]