In this research, the natural pyrite ore found in Tartous Governorate was described by studying the two samples taken from Hosn Suleiman -Safita (A) and Al Qadmous (B) area, in addition to studying the optimum conditions for pyrite dissolution (pH - time - quantity) with aerobic conditions. The results of X-ray diffraction (XRD) showed that the sample (A) is mainly composed of pyrite mineral and does not contain impurities, while sample (B) is composed of pyrite mineral combined with a small amount of calcite mineral, and these results were confirmed by the result of (FTIR) infrared spectroscopy and Polarised light microscopy (PLM(. The iron percentage in the two samples (A,B) is ranged between (42.6 – 43 %) and the sulfur percentage is between (40 – 53.7 %). With regard to pyrite dissolution, the results showed that pyrite taken from Hosn Suleiman (A) begins to dissolve at pH values less than 4.5, and the contact time is about 6 hours. By Comparing the results of sample (A) with sample (B), we found that the dissolution of sample (A) was about three times less than the dissolution of sample (B), and this is due to the fact that sample (A) contains pure and well crystallized pyrite ore while sample (B) contains pyrite combind with calcite, which increases its solubility.