Barwa nefrytu i ametystu w świetle najnowszych badań mineralogicznych

Abstract

COLOUR OF NEPHRITE AND AMETHYST IN THE LIGHT OF THE LATEST MINERALOGICAL STUDIES Summary The paper presents an attempt to explain the nature of colour of nephrite and amethyst with reference to the latest mineralogical studies. Colour of minerals is a complex physical phenomenon and its nature appears very difficult to explain. In order to achieve most accurate interpretation of the obtained data, the question of colour should be analysed with reference to structural-chemical, physical and genetic phenomena. The final result of interpretation of colour of minerals, the major problem of which is connected with complex physical nature of that phenomenon, is sometimes made closer by the set of spectroscopic methods, helpful in solving that problem. Leaving aside the details of physical nature of the analysed minerals of the silicate group it may be stated that colour of amethyst is influenced by Fe2+ and Fe3+ ions. This type of colour is assigned to the radiation colour group. In the case of nephrite, colour appears to be primarily related to Fe and Cr ions and assignable to the allochromatic colour group. Moreover, brief characteristics of the selected minerals is given.