CHAPTER 4 - The Rapid Analysis of Silicate Rocks

Abstract

This chapter discusses the rapid analysis of silicate rocks. The complete chemical analysis of silicate rocks using classical methods is very time consuming and requires the services of a skilled analyst. Classical rock analysis is based upon the technique of gravimetric analysis, which is a time consuming procedure. The schemes for the rapid analysis of silicate and other rocks are based upon the replacement of gravimetric procedures with other techniques that are simpler and more rapid. The schemes for the rapid analysis are frequently made in the presence of other elements, avoiding lengthy and tedious separation stages. Photometric methods are commonly used for the determination of titanium, manganese, and phosphorus—the elements that are present in small or minor amounts—where the accuracy and precision of spectrophotometric methods is adequate. Although photometric methods are frequently recommended for the determination of total iron, the precision obtainable is barely adequate for basic and other rocks rich in ferrous or ferric iron. For these rocks, a titrimetric method using potassium dichromate, potassium permanganate, or ceric sulfate solution provides an acceptable alternative to the photometric methods.