Silica Quartz Lumps

Product Description

X-ray fluorescence spectrometry analysis

The analyses were performed using the XRF Wavelength Dispersive Spectrometer (WDS-XRF) Philips PW***0, supplied to the Department of Earth Sciences. The analytical methodology used is that developed by Franzini et al. (***5). The accuracy of the analyses is less than 2%. The total iron was determined as Fe2O3. The Loss on Ignition (LOI) was determined by calcination at ***0°C for at least 1 hour of approximately 1 g of sample.
The analytical results obtained from the X-ray fluorescence spectrometry analysis were calibrated using calibration curves obtained by measuring a series of about *0 international standard certificates and some internal standards for high content of SiO2.


                                 Quartz 1    Quartz 2
       
Major (% weight)       
SiO2                         *9.*2        *9.*1
TiO2                         <0.*1        <0.*1
Al2O3                         0.*7          0.*8
Fe2O3tot                    0.*3          0.*2
MnO                         <0.*1        <0.*1
MgO                           0.*3        <0.*1
CaO                           0.*3          0.*4
Na2O                         0.*1          0.*2
K2O                         <0.*1        <0.*1
P2O5                       <0.*1        <0.*1
L.O.I.                          0.*2          0.*3
       
Trace (ppm)       
Ni                                4        3
Co                           <3        <3
Cr                               6        5
V                             <3        <3
Ce                         <3        <3
Nd                          <3        <3
Ba                       <*0        <*0
La                          <3        <3
Nb                          <2        <2
Zr                            <5        <5
Y                            <4        <4
Sr                          <6        <6
Rb                           4        4
Pb                         <2        <2
As                         <3        <3
Zn                          <2        <2
Cu                         <*5        <*5
S                           <*0        <*0
Cl                          <*0        <*0


ICP - MS Qualitative Analysis

The determination was carried out using the Thermo Fisher Scientific inductively coupled plasma Mass Spectrometer, X Series II, supplied to the Centro Interdipartimentale Grandi Strumenti [Interdepartmental Large Instruments Center]. The two samples were prepared in solution in Pt crucibles by means of alkaline fusion with LiBO2, in order to completely disperse the sample in a glass matrix; subsequently the fusion obtained was solubilized in HNO3 and the solution analyzed by ICP-MS instrumentation.
 
The spectra reported in Figures 1 and 2 show the presence of many trace or ultra-trace elements, as expected for samples of natural origin.
Although using pure reagents (LiBO2 flux and solubilizing HNO3) for the analysis, the level of impurities present in the reagents caused however, given the high sensitivity of the instrumentation, a significant disturbance on the instrument output, as evidenced by the "blank" spectrum (blank = solution prepared using only the same amount of flux and solubilizer used for the dissolution of the samples) in Figures 1 and 2.
Therefore the identification of the ultra-trace components present, certainly attributable to the matrix of the two samples, is not certain with this type of qualitative analysis. In any case, other than the elements for which the quantitative determination was done with X-ray Fluorescence Spectrometry, other elements should not be present in significant concentrations. In the event a quantitative evaluation of ultra-trace elements becomes necessary the request should be aimed at very specific groups of elements, and use therefore of targeted solubilization procedures with high purity reagents and standard solutions prepared ad hoc.
 

Bibliographical references

Franzini M., Leoni L. & Saitta M., (***5): Revision of a fluorescence analytical methodology, based on the complete correction of matrix effects. Rend. Soc. Ital. Mineral. Petrol. [Reports of the Italian Mineralogical and Petrological Society], *1, p. ******8.