Carbonaceous particle samples from an oil-fired power plant were collected by means of an in-stack isokinetic sampler. After a chemical and physical characterization of the carbonaceous particles collected, the successive formation of various crystalline species from the particles themselves was observed in controlled and environmental conditions. The morphology, chemical composition, and, when possible, the mineralogy of the single crystals found were studied. A progressive order of formation of the crystals, nucleated from the carbonaceous particles is reported herein. However, the correlation between the nature of the carbonaceous matrix, its chemical composition, and the order of formation of the crystals observed is still under investigation. -- AATA