Colour reactions in the micro-chemical determination of minerals

The rapid determination of the chemical elements present in a mineral has been a desideratum ever since minerals became of economic use. Various methods have been employed, starting with blowpipe work, which in the early days proved of great value, especially in experienced hands, With the development of chemistry and the discovery of new elements, this process was largely abandoned in favour of the standard ' wet method' of chemical analysis. Later on, micro-chemical reactions came into limited employment. Here the appearance of easily crystallizable salts under the microscope was used for diagnostic purposes. This method has been extensively examined of late years and became so overloaded with precautions that its chief asset, that of rapidity and case of employment, has been largely lost. Quite recently colorimetric reactions have been applied to qualitative analysis. These appeared so promising that the present author was encouraged to endeavour to apply them to the examination of minerals.A scheme for the qualitative determination of the commoner elements was published by G. Gutzeit in 1929, which at first sight looked very attractive.