Vis-NIR reflectance spectroscopy is a non-destructive, rapid, and inexpensive technique with minimal sample preparation and no damage to the environment. This study was carried out to assess the capability of vis-NIR spectroscopy to estimate and map selected chemical soil properties and dominant clay minerals in Isfahan province. A total of 251 surface soil samples were collected from the whole province. Spectral analysis was performed using a field spectrometer in 350-2500 nm range. Inverse distance weighting and kriging methods were used to map dominant clay minerals and chemical soil properties, respectively. Results showed that PLSR could predict organic matter and gypsum accurately. Prediction of gypsum was quite accurate and, therefore, vis-NIR spectroscopy could be used as an inexpensive approach to quickly estimate gypsum content of the soils in arid regions. Estimation of dominant clay minerals was not satisfactory which could be attributed to the influence of carbonates and gypsum on absorption features of clay minerals and effect of different clay minerals mixture in the soil. The spatial variability of soil organic matter, salinity and gypsum in the Isfahan province well follows the climatic varaibility while soil carbonates spatial variability is very much affected by the distribution pattern of soil parent materials. Both climate and parent materials have determined the spatial variability of palygorskite and expandable clay minerals in soils of the Isfahan province. Keywords : Visible and near infrared spectroscopy, Continuum removal, Clay mineralogy, Palygorskite, Illite, Smectite, Partial least squares regression
