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130
ANDRADA MĂICĂNEANU, HOREA BEDELEAN, SILVIA BURCĂ , MARIA STANCA
The chemical composition of the bentonites from Oraşul Nou is presented
in the table 1. It is worthy to note the relatively high Al 2O 3 and relatively low
Na2O contents.
Semi-quantitative mineralogical composition of clay raw material
realised by means of X-ray diffraction analysis, figure 1, indicated that in all
bentonite samples, smectite (montmorillonite) is the most abundant clay
mineral. Identified minerals were: smectite (montmorillonite), cristobalite, quartz,
feldspars. The basal space was recorded at 15 Å, indicating the precence of
Ca-montmorillonite [11].
The montmorillonite amount varies between 20-85%, according to
the alteration degree of the rock; locally, it may even reach values of 95%.
Oxides,
[%]
Oraşul
Nou
Table 1. Chemical composition of the bentonite samples from
Oraşul Nou (Satu-Mare County).
SiO 2 Al 2 O 3 Fe 2 O 3 CaO MgO Na 2 O K 2 O TiO 2 L.O.I.
60.62
-71.46
15.40
-23.55
0.84
-2.34
1.18
-1.86
0.54
-2.05
0.00
-0.30
0.25
-2.16
0.15
-0.36
Figure 1. Powder X-ray diffractogram of the Oraşul Nou bentonite sample;
Mm- montomorillonite, Cr-cristobalite, Q-quartz, Fp-feldspar.
8.69
-12.4
Examination of IR spectra of the bentonite sample (figure 2), indicates
the presence of specific 2:1 clay mineral peaks (montmorillonite) with peaks
in 600-700 cm -1 region that could be attributed to illite, clinoptilolite or opal
CT accompanying minerals [12-19]. The identified peaks can be attributed