3. Mineralogy

The six PGMs have similar ionic radii, so there are many solid solutions between them (table 1 ).

In geochemistry, platinoids were long considered to be highly siderophilic, but the most recent discoveries of new minerals have been sulfides, selenides, tellurides and sulfo-arsenides. Platinum-bearing minerals occur in very small quantities in silicates, as they were concentrated during the first stages of magmatic differentiation. They are therefore mainly found in mafic and ultramafic magmatic rocks (magnesium-iron rocks) and associated deposits