Various methods of detailed observation may be applied, such as the measurement of the size of the elements of the rock by the help of micrometers, their relative proportions by means of a glass plate ruled in small squares, the angles between cleavages or faces seen in section by the use of the rotating graduated stage, and the estimation of the refractive index of the mineral by comparison with those of different mounting media.
Various techniques of precise observation can be employed, including measuring the dimensions of rock elements using micrometers, determining their relative proportions by comparing them to a glass plate divided into small squares, assessing the angles between cleavages or faces observed in section with the aid of a rotating graduated stage, and estimating the refractive index of the mineral by comparison with those of different mounting media.