The paper is focused on the micro and nano organization of atmospheric particulate matter in Grigorescu district of Cluj-Napoca in April and May 2017. Floating particles (FP) collected from atmosphere have an increased amount of minerals such as: quartz, calcite, clays (e.g. kaolinite and muscovite), and traces of lepidocrocite. Their size varies from less than 1 to over 120 μm, established by Scherer method on an XRD pattern. PM10 contains mainly quartz and calcite followed by fractions of kaolinite and muscovite. PM2.5 contains clay in large amount and less quartz particles. Certain nanoparticles are found among PM2.5. The obtained values were in good agreement to TEM and AFM microscopy. The diameters are 42 nm for clay and 92 nm for quartz particles. Nanostructural features are organized around fine micro particles such as PM 2.5. PM10 is often found as particles around FP.