1. A method of determining the mineral present at a point in a sample of unknown composition, comprising: directing an electron beam toward a point on the sample to acquire an x-ray spectrum; providing multiple mineral definitions, each mineral definition including a list of elements, each of the elements having a corresponding standard spectrum; comparing the acquired spectrum to a combined standard spectra of the elements from the element list of a first mineral definition; comparing the acquired spectrum to a combined standard spectra of the elements from the element list of a second mineral definition; determining which of the combined standard spectra of elements from mineral definitions best matches the acquired spectrum; and classifying the point on the sample as being composed of the mineral whose definition produced the best match.