X-Ray Laboratory

X-Ray Diffraction

The X-Ray lab has a Malvern Panalytical X’Pert PRO X-ray diffractometer (XRD) equipped with a 15-position sample changer and a ceramic Cu X-ray tube. Standard phase identification and Rietveld analysis are our forte. Students, staff, and faculty in the Departments of Earth and Environment, Chemistry and Physics use the XRD. Examples of student and faculty XRD research include identification of minerals in rocks, soils and lake sediment, characterizing nanoparticles, and the properties of synthetic double chain salts.

X-Ray Diffraction

X-Ray Fluorescence

Our other major X-ray research instrument is the Malvern Panalytical Zetium X-ray fluorescence (XRF) vacuum spectrometer that was installed and calibrated in mid-January 2019. A major step forward with this generation of XRF spectrometers is the 4kW Rh super sharp X-ray tube that maintains its output x-ray intensity over the life of the tube. The sample deck is capable of holding 68 individual samples when fully loaded. View accuracy data here.

• Cutting & Crushing Sample Preparation Techniques
• Loss on Ignition (LOI) – Determining the Total Volatile Content
• Major Element Technique
• Trace Element Technique (Copolywax - Whole Rock Powder Preparation)
• Ferrous Iron Determination

Sample preparation for major element analysis

To start, a total volatile determination (% LOI) is made by weighing out ~1 gram of sample to 4 decimal places, placing in a muffle furnace at 950C for 1.5 hours, removing and cooling to room temperature in a desiccator, and re-weighing and noting the weight change. A portion of this anhydrous sample powder (0.4000 +/- 0.0001 grams) is mixed with lithium tetraborate (3.6000 +/- 0.0002 grams), placed in a platinum crucible and heated with a meeker burner until molten. This molten material is swirled and mixed several times over 10-12 minutes and transferred to a platinum casting dish and quenched. This procedure produces a glass disk that is used for XRF analysis including SiO2, TiO2, Al2O3 , Fe2O3 Total, MnO, MgO, CaO, Na2O, K2O, and P2O5.

Working curves for each element are determined by analyzing geochemical rock standards prepared exactly as described in the paragraph above. (See Abbey (1983) and Govindaraju (1994) for chemical analyses of the rock standards). Between 50 and 60 data points are gathered for each working curve; various element interferences are also taken into account. Results are calculated and presented as percent oxide.

Working curves for each element are determined by analyzing geochemical rock standards prepared exactly as described in the paragraph above. (See Abbey (1983) and Govindaraju (1994) for chemical analyses of the rock standards). Between 50 and 60 data points are gathered for each working curve; various element interferences are also taken into account. Results are calculated and presented as percent oxide.

Ferrous iron titration and Loss on Ignition

The amount of ferrous Fe is determined by the titration using a modified Reichen and Fahey (1962) method. XRF determines total iron as Fe₂O₃. Loss on ignition is determined by heating an exact aliquot of the sample at 950^o C for 1.5 hours.

Preparation for XRF trace element analysis

Trace element analysis is accomplished by weighing out 7.0000 +/- 0.0004 grams of whole rock powder and adding 1.4000 +/- 0.0002 of high purity copolywax powder, mixing for 10 minutes, and pressing the powder into a briquette at 50,000 psi. Data are reported as parts per million (ppm) for Rb, Sr, Y, Zr, V, Ni, Cr, Nb, Ga, Cu, Zn, Co, Ba, U, Th, La, Ce, Sc, Pb, and Mo. Working curves for each element are determined by analyzing geochemical rock standards prepared exactly as outlined above, data for which has been synthesized in Abbey (1983) and Govindaraju (1994). Between 50 and 60 data points are gathered for each working curve; various elemental interferences are also taken into account. The Rh Compton peak is utilized for a mass absorption correction for region one elements.

Important

Always keep in mind that the original rock or mineral powder must be crushed so the ALL of the sample passes through a clean 80-mesh sieve screen. Do NOT use Tungsten Carbide grinding vessels if at all possible. Always use alumina or ceramic crushing implements if  available.

The personnel who handle day-to-day operation of the X-ray instrumentation are:

• Dr. Stan Mertzman, Senior Research Associate
• Emily Wilson, Research Laboratory Manager and Technician
• Karen Mertzman, Laboratory Technician

XRF: Zetium sample changer

References

Abbey, S., 1983, Studies in “Standard Samples” of silicate rocks and minerals 1969-1982: Geological Survey of Canada Paper 83-15, pp. 1-114.

Bennett, H. and Oliver, G. 1992, XRF Analysis of Ceramic, Minerals and Allied Materials, John Wiley & Sons, LTD (ISBN 0 471 93457 7 (cloth)) pp. 298.

*Boyd, F.R., and Mertzman, S.A., (1987): Composition of structure of the Kaapvaal lithosphere, southern Africa: In Magmatic Processes- Physiochemical Principles, B.O. Mysen, Ed., The Geochemical Society, Special Publication #1, pp. 13-24. (Contains description of XRF
methodology).

Govindaraju, K. 1994: Compilation of Working Values and Sample Description for 383 Geochemical standards: Geostandards Newsletter, Vol. 18, Special Issue, pp. 1-58.

Jenkins, R., 1999, X-Ray Fluorescence Spectrometry, 2 nd ed., John Wiley & Sons, Inc. (ISBN 0-471-29942-1 (cloth)) 207 pp.

*Mertzman, S.A., 2000, K-Ar results from the Southern Oregon- Northern California Cascade Range. Oregon Geology, V. 62, no. 4, pp.99-122.

Reichen, L.E. and Fahey, J.J, 1962, An Improved Method for the Determination of FeO in Rocks and Minerals Including Garnet. U.S. Geological Survey Bulletin 1144B, pp. 1-5.

*Waterton, P., Pearson, D. G., Mertzman, S. A., Mertzman, K. R., Kiarsgaard, B., 2021, Komatiites, basalts and dunites: Plumbing system of a Proterozoic greenstone belt: Jour. Petrology, V. 61, no. 5. See: https://doi.org/10.1093/petrology/egaa052 

* Most useful references.

FedEx or UPS packages should be addressed:

C/O Warehouse
Dr. Stan Mertzman
Franklin and Marshall College
415 Harrisburg Avenue,
Lancaster, PA 17603-2615

Using the regular U.S. Postal Service address packages to:

Dr. Stan Mertzman
Department of Earth and Environment
Franklin and Marshall College
PO Box 3003
Lancaster, PA 17604-3003