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Institut für Geographie und Geologie

Electron Microprobe

The Department of Geodynamics and Geomaterial Research has a GEOL JXA-8800L electron beam microprobe with four wavelength dispersive spectrometers (monochomator crystals TAP, PET, LIF). The device is well suited for qualitative investigations and for quantitative point analyses of major and minor elements in micro range and in structural environment. A scanning electron microscope device allows visualisation of the secondary electron images and the backscattered electron imaces. The focal points of the analysis, in accordance with the research interests of the department, are petrological, ore petrological, material scientific and archaeometric questions. For the analysis of samples in atypical formats, like archaeological finds, a special sample holder is available.

In addition to the department-internal users, the microprobe laboratory can also be used by external guests. We ask for early consultation regarding the analytical questions, the deadline for the performance of the measurements and the costs:

U. Schüßler, Phone 0931-31-85422 oder uli.schuessler@uni-wuerzburg.de

User´s regulations for the microprobe lab


Measurement conditions for routine analysis:

  • Accelerating voltage 15 kV
  • Beam current 20 nA
  • Beam diameter 1 - 30 microns
  • Counting times 20 s/peak and 20 s/background
  • Standards ares simply composed element-, oxide- and mineral standards
  • Matrix correction ZAF
  • Analytical error for major elements < 1% relativ (Na < 2%)
  • Detection limit for trace elements 500 - 1000 ppm

For special applications, these measurement conditions may be modified.

For reasons of comparison, our laboratory was involved in a circle analysis, in which a total of 26 European microprobe laboratories participated. Our results (Lab #1 in the result table) are well within the range of variation of the other laboratories:

Electron microprobe circle analysis

To get information about the general reliability of electron microprobe analyses carried out in different laboratories with different machines, an international circle analysis project was initiated and organized from 1994 on. A sample holder was produced containing three homogeneous mineral samples typical for petrological material:

  • Olivine from St. John, Scotland, contributed by A. Kirfel, Institut for Mineralogy and Petrography, University Bonn
  • Garnet, synthetic, contributed by T. Fehr, Institute for Mineralogy, Petrology and Geochemistry, LM University Munich
  • Feldspar, Lake County, Oregon, contributed by J. Koepke, Institute for Mineralogy, University Hannover

The sample holder was in succession sent to 26 participating labs and was newly polished and cleaned after coming back from each lab. Each lab measured minimum 10 spots on each mineral under routine analytical conditions and submitted the analyses with average and standard deviation (1 s) before knowing about the results of the other labs.  

The following table gives an overview concerning the variability of data of all 26 labs with minimum and maximum values measured, the difference between minimum and maximum values, the average of analyses from all labs with 1 s standard deviation and, calculated from this, the relative interlaboratory error:

 

minimum

maximum

max - min

average

1 s

1 s

 

wt.%

wt.%

wt.%

wt.%

wt.%

relativ

Feldspar

 

 

 

 

 

 

 

 

 

 

 

 

 

SiO2

49.65

52.47

2.82

51.27

0.60

1.2

Al2O3

28.35

31.79

3.44

30.17

0.68

2.3

MgO

0.05

0.18

0.13

0.13

0.03

23.1

CaO

13.02

14.39

1.37

13.65

0.29

2.1

FeO

0.38

0.47

0.09

0.44

0.02

4.6

Na2O

3.36

3.95

0.59

3.72

0.15

4.0

K2O

0.11

0.15

0.04

0.13

0.01

7.7

Total

 

 

 

99.51

 

 

 

 

 

 

 

 

 

Garnet

 

 

 

 

 

 

 

 

 

 

 

 

 

SiO2

40.27

41.74

1.47

41.10

0.44

1.1

TiO2

0.40

0.46

0.06

0.43

0.01

2.3

Al2O3

22.24

24.19

1.95

23.04

0.41

1.8

MgO

16.15

18.45

2.30

17.24

0.46

2.7

CaO

5.33

6.46

1.13

5.79

0.19

3.3

MnO

0.32

0.37

0.05

0.35

0.01

2.9

FeO

11.67

12.75

1.08

12.37

0.26

2.1

Total

 

 

 

100.32

 

 

 

 

 

 

 

 

 

Olivine

 

 

 

 

 

 

 

 

 

 

 

 

 

SiO2

39.37

41.34

1.97

40.62

0.42

1.0

MgO

47.98

50.44

2.46

49.35

0.56

1.1

MnO

0.11

0.15

0.04

0.13

0.01

7.7

FeO

9.11

10.93

1.82

9.65

0.32

3.3

NiO

0.21

0.39

0.18

0.34

0.03

8.8

Total

 

 

 

100.09

 

 

A table with the average compositions from each lab together with intralaboratory standard deviation is available here(table of results). The labs remain anonymous and are marked by numbers. The order of labs in the table is not consistent with an alphabetic list of the participating institutes at the end of this page.

For the future, the sample holder used for the circle analysis is available for all microprobe labs as a tool to check the own analytical reliability concerning silicate minerals. The sample holder will be delivered with newly polished samples, but without carbon coat. Please turn to

Uli Schüssler, Phone +49-931-888-5422 or uli.schuessler@uni-wuerzburg.de

The following institutes and labs have participated in the circle analysis:

GERMANY
  • Bayreuth: Bayerisches Forschungsinstitut für experimentelle Geochemie und Geophysik der Universität (Volker von Seckendorff)
  • Berlin: Zentraleinrichtung Elektronenmikroskopie (ZELMI) der TU (Francois Galbert)
  • Bochum: Zentrale Elektronen-Mikrosonde der Ruhr-Universität (Heinz-Jürgen Bernhardt)
  • Bonn: Mineralogisch-Petrographisches Institut der Universität (Jürgen Ehl)
  • Clausthal-Zellerfeld: Institut für Mineralogie der TU (Karsten Gömann, Klaus Hermann)
  • Darmstadt: Fachbereich Chemische Analytik der TH (Sebastian Riedl)
  • Frankfurt am Main: Institut für Mineralogie der Universität (Thomas Stachel)
  • Freiburg: Institut für Mineralogie, Petrologie und Geochemie der Universität (Hiltrud Müller-Sigmund)
  • Giessen: Institut für Geowissenschaften und Lithosphäreforschung der Universität (Rüdiger Borchardt)
  • Göttingen: Zentrum Geowissenschaften der Universität, Abt, Geochemie (Andreas Kronz)
  • Hamburg: Institut für Mineralogie der Universität (Barbara Cornelisen)
  • Hannover: Institut für Mineralogie der Universität (Jürgen Koepke)
  • Heidelberg: Mineralogisches Institut der Universität (Hans-Peter Meyer)
  • Kiel: Geomar Forschungszentrum (Petra Glöer)
  • Kiel: Mineralogisch-Petrographisches Institut der Universität (Dietrich Ackermand, Barbara Mader)
  • Köln: Mineralogisch-Petrographisches Institut der Universität (Gudrun Witt-Eickschen)
  • Mainz: Institut für Geowissenschaften der Universität, Mineralogie (Burkhard Schulz-Dobrick)
  • Mainz: Schott Glaswerke, Abt. Glasfehleranalytik/Mineralogie (Bernhard Valentin)
  • München: Institut für Mineralogie, Petrologie und Geochemid der LM Universität (Thomas Fehr)
  • Münster: Institut für Mineralogie der Universität (Michael Enders)
  • Potsdam: GeoForschungsZentrum GFZ (Dieter Rhede,Wolfgang Seifert)
  • Würzburg: Institut für Mineralogie der Universität (Uli Schüssler)
AUSTRIA
  • Wien: Institut für Petrologie der Universität (Theodoros Ntaflos)
FINLAND
  • Espoo: Geologian Tutkimuskeskus (geological survey), Espoo (Kari Kojonen)
SWEDEN
  • Uppsala: Institutionen för Geovetenskap, Mineralogi-Petrologi, Universitet Uppsala (Hans Annersten
SWITZERLAND
  • Basel: Mineralogisch-Petrographisches Institut der Universität (Susanne Schmidt)

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Contact

Chair of Geodynamics and Geomaterials Research
Am Hubland
97074 Würzburg

Phone: +49 931 31-85421
Fax: +49 931 31-87345
Email

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