As previously told in the introduction, we can find articles about calcite Raman spectra as soon as the effect had been discovered. To find remarkable results, however, we must wait until 1942 and 1945, when Rappal Sangameswaran Krishnan obtained his Raman spectra of calcite and gypsum. Regarding the experiment, we find that the spectra, as obtained by Roop Kishore, 1942, and then by show "far greater detail than any [spectrum] recorded by others not only in gypsum but in other crystalline hydrates as well. The success is due to the use of the intense mercury resonance radiation for exciting the Raman spectrum" . In fact, if we consider the region of Raman spectrum regarding the gypsum crystallization water, we find an excellent agreement between the Krishnan's data and the decomposition we can obtain by means of q-Gaussian functions of RRUFF spectra (Sparavigna, Zenodo). the development of a remarkably useful technique for the study of the Raman effect, the value of which has been demonstrated by the resounding success with which he himself applied it in several cases of fundamental interest" . Rasetti proposed to use "the 2537 A.U. monochromatic radiations of mercury vapour under special conditions which ensured that only this radiation and none other would give an observable Raman effect. The technique consists in using a low-pressure quartz mercury arc in which the mercury vapour is prevented from reaching any considerable density, and from absorbing the 2537 radiation emitted by itself. This is accomplished firstly by very effective water-cooling, and secondly by squeezing the discharge against the walls of the quartz tube by the field of a specially designed electromagnet. A filter of mercury vapour at room temperature is placed in the path of the scattered light emerging from the substance under study to absorb the 2537 radiation. This filter works so effectively that some of the feeble mercury lines which have intensities negligibly small in comparison with the 2537 radiations and which therefore give no observable Raman effect nevertheless appear stronger than the 2537 line in the recorded spectra" .