Sources and characteristics of particulate matter (PM) were determined in a modern underground chrome mine in Finland. Measurements were conducted at five locations in the mine: the maintenance area, blasting area, ore pit dumping area, crushing station and conveyor belt. The measurement set-up consisted of a Soot Particle Aerosol Mass Spectrometer (SP-AMS) for particle chemical composition, Electrical Low Pressure Impactor, nano-Scanning Mobility Particle Sizer and Optical Particle Counter for particle number and mass size distribution, and Aethalometer for black carbon (BC). Particle number and mass concentration depended strongly on the measurement location and period. PM10 varied from 22 to 1100 µg m-3 and total number concentration from 1.7 x 103 to 2.3 x105 # cm-3 in the mine. In terms of chemical composition, submicron particles (PM1) consisted mostly of organic matter and BC, but at the blasting site also the fraction of sulfate was significant. The SP-AMS data was analyzed with Positive Matrix Factorization (PMF) to identify and quantify the main sources of PM1 in the mine. Based on the PMF analysis, PM1 originated mostly from diesel engines (35–84%) and blastings (7–60%). The impact of blastings on mine air quality may become more pronounced in future as the emissions from diesel engines decrease due to alternative fuels and better engine and after-treatment technologies.