A set of five manuscripts written by Sister Lúcia between 1941 and 1944 were under study. Among them is the one that contains the description of the third part of the Secret of Fátima also known as the Third Secret of Fátima. In this work, a characterization of the paper and the ink used in these documents was achieved using micro-X-ray fluorescence spectrometry. Quantitative results were obtained for P, K, Ca, Fe, Cu and Zn, revealing different paper composition and Zn in the inks. 2D elemental maps confirmed that Zn was present in the five documents ink and that the manuscript revealing the Third Secret of Fátima contained no erasures or alteration attempts to the original manuscript.