A novel approach in the mineralogy of Carpathian mahogany obsidian using complementary methods

Besides the PGAA measurements of the bulk elemental composition, Mössbauer spectroscopy and transmission electron microscopy (TEM) were used to study the samples in order to identify the presence of ferrous or ferric iron. With the help of Small Angle Neutron Scattering (SANS), the bulk nanostructures of the samples have been investigated and their surface or volume fractal dimensions have been determined. Black obsidians showed isotropy, while mahogany samples displayed a considerable anisotropy in the bulk pore orientation. According to our results, a large amount of the iron is dominantly located in different phases in the case of mahogany and black obsidians. Based on the summarised results, the differences between the red and black variants can be also explained by the different oxidation states of the Fe-ions, which may explain the colour difference.