Comparative studies of structural transformations of carbonate and silica minerals by means of thermosonimetry and differential thermal analysis

• Published in: Thermochimica acta 1984, Vol.72 (1), p.159-163
• Main Authors: Lønvik, K, Smykatz-Kloss, W
• Format: Article
• Language: English
• ISSN: 0040-6031; 1872-762X
• DOI: 10.1016/0040-6031(84)85068-6

Many minerals exhibit structural transformations between low- and high-temperature modifications the nature and mechanism of which are not yet completely clear. Physical defects and chemical impurities influence the shape, and temperatures of the transformation effects. Especially the fine-grained, micro-and crypto-crystalline species of silica (e.g. agates, jasper, chrysoprase etc.) show a broadening of the low-high inversion effect, lower intensity (ΔT) of the peaks and lower inversion temperatures, compared with well crystallized quartz crystals. These effects can be measured by DTA. But this technique do not have resolution good enough in case of overlapping effects. This is much better in thermosonimetry (TS). The combination of DTA and TS enables the exact determination of the nature of structural transformations (DTA) in dependence on the physical defect character of the minerals (TS). The present paper includes the data of the minerals strontianite (SrCO 3), witherite (BaCO 3), well and badly crystalline quartz (e.g., rose and smoky quartz, jasper, agate, chrysoprase) and cristobalite.