The object of this study was to analyze mineral particles in lung tissue from a farmer who underwent lobectomy due to a lung tumor and relate these analytical findings to occupational exposure and histopathological and clinical diagnoses. Despite no clear evidence of previous occupational dust exposure, heavy deposits of birefringent particles and slight pulmonary fibrosis were found during histopathological examination. Extracts from the lung tissue were analyzed by electron microscopy and X-ray microanalysis for mineral particles. The major components of the dust were identified as mica, talc, and silica. Minor components included asbestos fibers and rutile fibers. Some of these fibers were coated by ferroproteins. Mica, quartz, feldspars (plagioclase), and rutile fibers were found in the soil from the farmer's potato storehouse. Based on these findings it is assumed that the slight pulmonary fibrosis is probably caused by the different mineral particles deposited.