A technique has been developed for X-ray analysis using energy dispersive solid state detectors commonly used with electron microprobes or scanning electron microscopes (SEM). This technique does not require the use of analysed standard alloys, instead the elemental peaks are directly compared to each other and simple corrections applied to convert these to weight percentages. A new empirical table for X-ray fluorescence yields for the L X-ray spectra is also given in this article.
In a specimen which is transmission thin to 100 kV electrons - a sample in which X-ray absorption is so insignificant that it can be neglected and where fluorescence effects can generally be ignored (1,2) - a ratio of characteristic X-ray intensities, I1/I2 can be converted into a weight fraction ratio, C1/C2, using the equationwhere k12 is, at a given voltage, a constant independent of composition or thickness, k12 values can be determined experimentally from thin standards (3) or calculated (4,6). Both experimental and calculated k12 values have been obtained for K(11<Z>19),kα(Z>19) and some Lα radiation (3,6) at 100 kV. The object of the present series of experiments was to experimentally determine k12 values at voltages between 200 and 1000 kV and to compare these with calculated values.The experiments were carried out on an AEI-EM7 HVEM fitted with an energy dispersive X-ray detector.
The Bondoc Peninsula meteorite appears to be unstable and is disintegrating as the result of terrestrial corrosion. The meteorite is complex with occasional 1 to 3 cm dia. ‘Nodules’ of ‘iron-class’ material, fig. 1, within which are numerous non-metallic inclusions. These range in size from 0·5–1·5 mm and vary in shape from the extremes of angular to globular, shown in figs. 2 and 3. The metallic groundmass of fig. 1 is a polycrystalline array of kamacite grains that are equant in shape and about 3 to 4 mm dia. The boundaries between these kamacite grains are heavily invaded by corrosion product. The films of cracked schreibersite and strips of compositionally zoned taenite that are present at the kamacite boundaries each contribute about 2 % by volume and their average Ni contents are about 45 wt% and 40 wt% respectively. When these figures are combined with the average 6·2 wt% Ni, 0·75 wt% Co, and 0·02 wt% P of the kamacite the resulting bulk composition of the metal is ∼ 7·5 wt% Ni, ∼ 0·7 wt% Co, ∼ 0·3 wt% P. Nital etching reveals partially annealed Neumann bands in the kamacite, indicating a late stage reheating below about 500°C. However, the M profile method of Wood (1967) when applied to the zoned taenite yields a cooling rate of 0·1–0·5°C/Myr before this reheating event.The angular inclusions are relatively coarsely crystalline and commonly have massive chromite and tridymite crystals, with pyroxene, anorthite, and whitlockite usually present. Most angular inclusions also contain small particles of metal (10–40 µm dia.) interstitial to the mineral phases in the depth of the inclusion. Small quantities of sulphide and phosphide are similarly located. The metal in the angular inclusions is not detectably zoned and both kamacite and taenite show a range of Ni contents that vary with particle size in the manner previously observed by Powell (1969) for a range of conventional mesosiderites. We have in addition measured the Co and P contents of this metal and find P < 0·1 wt% and the Ni and Co analyses are consistent with equilibration in the ternary Fe-Ni-Co equilibrium diagram at ∼ 450 °C.
Mount Kinabalu consists of granites at its core on the higher ground of the mountain, and is surrounded by sedimentary rocks of Trusmadi formations at its foot, with the occurrences of serpentinised ultrabasic rocks found between the granites and sedimentary rock at the elevation of 2000m to 2800m. The granite is subdivided into hornblende granite, biotite granite and porphyritic granite. The porphyritic granite is found in a belt between serpentinite in the lower part and hornblende granite in the upper part of the mountain. A ground magnetic data acquisition was conducted in May 2013 along the tracks from Mesilau to the summit of Mount Kinabalu and from summit down at Timpohon gate. The processed magnetic data shows distinctive magnetic characteristics that correlate very well with three different rock formations of Mount Kinabalu. Large variations of total magnetic total field from 39400nT to 41700 nT (magnetic variation range of 2300nT) were observed within the serpentinised ultrabasic rocks. It is believed that this distinctive magnetic characteristic is due to occurrence of ferromagnetic minerals, which was formed as a result of serpentinisation of ultrabasic rock with the presence of water during deep seated hydrothermal activity. The total magnetic field within the granite zone decreased gradually from the edge of serpentinite to the hornblend granite near the summit with relatively smaller variations from 40900nT to 39990nT (magnetic variation range of 910nT), probably due to small percentage of magnetite in it. The Trusmadi sedimentary formation in lower altitudes was magnetically "stable", with the small magnetic variation from 40000nT to 40385 nT (magnetic variation range of 385nT).
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