A method of identifying a material using an x-ray emission characteristic is provided. X-ray data representing a monitored x-ray emission characteristic is obtained from a specimen in response to an incident energy beam. A dataset is also obtained, this comprising composition data of a plurality of materials. The material of the specimen is contained within the dataset. Predicted x-ray data are calculated for each of the materials in the dataset using the composition data. The obtained and the predicted x-ray data are compared and the likely identity of the material of the specimen is determined, based upon the comparison.