Quantitative analysis of pyroxene (EPMA)

EPMA quantitative analysis of pyroxene
The CAMECA Electron Probe Microanalyzers offer experimental conditions that combine low accelerating voltages with intense beam currents. Under such optimized conditions, the interaction volume between the electrons and the specimen is reduced, and high spatial resolution can be achieved.

X-ray maps were acquired on exsolution lamellae of clinopyroxene in orthopyroxene. The lamellae are only a few hundreds of nanometers wide. Both phases were analysed with a fully focused spot, demonstrating the high spatial resolution capabilities of our EPMA.

The X-ray maps acquired on Ca and on Mg illustrate the unique ability of our EPMA instruments to combine low beam voltage for spatial resolution optimization with high sensitivity crystals for X-ray detection optimization.

Quantitative analysis was then performed in both clinopyroxene and orthopyroxene phases using a focused electron beam of 8keV and 20nA. The datasets below demonstrate the superior capabilities of the CAMECA Electron Probe Microanalyzers to determine accurate quantitative elemental composition.

Orthopyroxene quantitative analysis:

Na2O
MgO
SiO2
Al2O3
CaO
FeO
MnO
Total
3/1 0.001 31  54.84
1.14 0.73 11.09
0.26 99.06
7/1 0.03 31.04  54.77 1.13 0.62 12.3
0.29 100.2
8/1 0.01 31.09  54.54
1.15 0.72
11.77
0.88 100.16
9/1 0.01 30.85 54.54
1.11 0.79
12 0.71 100.02
12/1 0.02 30.8  54.71
1.11 0.68
11.52 0.23 99.09
Average 0.02 30.96
54.68
1.13 0.71
11.74 0.47 99.71

Clinopyroxene quantitative analysis:

Na2O
MgO
SiO2
Al2O3
CaO
FeO
MnO
Total
4/1 0.44  16.81
51.99
1.68 25.48
3.37
0.06 99.83
5/1 0.38 17.29
52.18 1.28 25.38
3.44
0.15 100.1
6/1 0.43 16.35
52.35
1.58 25.54
3.72
0.21 100.18
10/1 0.41 16.95
52.56
1.65 25.68
3.02
0.39 100.66
11/1 0.45 16.79
52.54
1.68 25.59
3.67
0.05 100.77
Average 0.42 16.84
52.32
1.57 25.53
3.44
0.17 100.31