chemistry function

Chemical Elements and Oxides

Identify oxides and major, minor and traces elements in a compositional data matrix. methods

is_element_major(object, ...)

is_element_minor(object, ...)

is_element_trace(object, ...)

is_oxide(object, ...)

## S4 method for signature 'character'
is_oxide(object)

## S4 method for signature 'CompositionMatrix'
is_oxide(object)

## S4 method for signature 'CompositionMatrix'
is_element_major(object, min = 1/100, max = Inf)

## S4 method for signature 'CompositionMatrix'
is_element_minor(object, min = 0.1/100, max = 1/100)

## S4 method for signature 'CompositionMatrix'
is_element_trace(object, min = -Inf, max = 0.1/100)

Arguments

• object: A CompositionMatrix object.
• ...: Currently not used.
• min: A length-one numeric vector specifying the lower bound for element identification.
• max: A length-one numeric vector specifying the upper bound for element identification.

Returns

A logical vector.

Details

There is no definite classification of what are the major, minor and trace elements are. By default, the following rule of thumb is used:

• major elements: The major elements are those that define the material under study. Major elements usually have concentrations of above 1%.
• minor elements: Minor elements usually have concentrations between 1% and 0.1%
• trace elements: Trace elements usually have concentrations of less than 0.1%.

Note

is_oxide() uses a regular expression (it does not check if elements exist or if stoichiometry is valid).

Examples

## Data from Day et al. 2011
data("kommos", package = "folio") # Coerce to compositional data
kommos <- remove_NA(kommos, margin = 1) # Remove cases with missing values
coda <- as_composition(kommos, groups = 1) # Use ceramic types for grouping

is_element_major(coda)
is_element_minor(coda)
is_element_trace(coda)

is_oxide(coda)

Author(s)

N. Frerebeau