BOX PAR1: SUMMARY AND INTERPRETATION OF INCLUSIONS IN
BLUISH-GREEN TOURMALINES FROM MOZAMBIQUE (FIG. PAR69-71):

The following inclusion features were found: Orangy filled growth tubes and cracks (Fig. Par68a-c and 69d) without or with purple halos (Fig. Par68b-c and 69a-d), opaque inclusions with purple halos (Fig. Par70c) and 2- and 3-phase fluid inclusions (solid, liquid and vapor) (Fig. Par71a-c). All observation was made in faceted samples (Fig. Par67b) originating from the same unheated tourmaline rough (Fig. Par67a-b). ED-XRF analysis in wt.-%, averaged from a number of measurements (in brackets) and divided into color groups (Definition Type C, see Fig. Par90)

These tourmalines were classified as Type C (See Fig. Par90a-b). For the chemical compositions of minor elements of the tourmalines of this inclusion case study see the inlayed table. These tourmalines are characterized by high Mn-concentrations. A theory of the formation of the “purple” halos was published at the printing date of this report (Lit. Par48). It is believed that these halos were produced by irradiation. During LA-ICP-MS analysis of orangy contaminations in the tubes and cracks, we detected isolated uranium-concentrations that are 10x higher than the concentrations found in the tourmaline matrix and about 30-60x above the detection limit (0.01ppm) in two different samples (Fig. Par76g and 78g). The presence of this radioactive element in the orange materials is support for the theory of formation of the “halos” by irradiation (Lit. Par48). Furthermore, “halos” are also observed around isolated solid inclusions that are not associated to cracks and tubes (Fig. Par70c). This is further supporting the theory. The “halos” around these inclusions, however, occur from the radiation that are produced by the mineral inclusion itself and not from contaminated orange colored substances. Elevated Cu-concentrations were not found in the orange zones (Other elements present, see Fig. Par76a-f and 78c-g).

Par71a-b Fluid inclusions were frequently present in these Mozambique tourmalines. The picture shows 2-phase inclusions found in a sample originating from the same rough of Fig. Par67a. Note that the fluid inclusion tubes do not have any expansion cracks. Therefore, no indications are present that the tourmaline has been subjected to a heat-treatment.