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Mineral Analysis
N G Ware, Australian National University, Canberra,
ACT, Australia
ß 2005, Elsevier Ltd. All Rights Reserved.

Mineral Analysis
Mineral analysis involves determining the chemical
relationships between and within mineral grains.
Microanalytical techniques are essential, and methods

include X-ray spectrometry and mass spectrometry.
Electron probe and laser ablation procedures are
commonly used techniques for major and trace
element analysis, respectively (see Analytical
Methods: Geochemical Analysis (Including X-Ray)).
A chemical analysis of a mineral is expressed as
a table of weight percent (wt.%) of its component
elements or oxides. Concentrations lower than about
0.5 wt.% are often expressed as parts per million
(ppm) by weight of element. These mineral analyses
are easily converted into atomic formulas and thence
into percentages of the end-member ‘molecules’
within the mineral group (see Table 1). Mineral analyses are used in descriptive petrology, geothermometry, and geobarometry, and in the understanding
of petrogenesis. Sometimes thousands of analyses are

collected in the completion of a single research project. Large amounts of data are presented graphically,
plotting concentrations of elements or ratios of elements against each other, thus illustrating chemical
trends or chemical equilibrium (see Figure 1).
In addition to the chemical analysis, a complete
description of a mineral requires a knowledge of its
crystallography. Both chemical composition and crystallography are required to predict the behaviour of
minerals, and hence rocks, in geological processes.
The discovery of each new mineral involves the determination of its crystal structure as a matter of routine
using X-ray and electron diffraction techniques.
Thus, when a monomorphic mineral is identified
from its composition, its crystallography follows.
Polymorphs may be identified by optical microscopy.
Whereas it is sometimes convenient to identify an
unknown mineral from its diffraction pattern, and
although cell parameters can be used as a rough measure of end-member composition, crystallography no

longer plays a major role in quantitative mineral
analysis.
It was once necessary to separate a mineral from its
parent rock by crushing, followed by use of heavy
liquids and magnetic/isodynamic separators. Up to a