An x-ray spectrometer includes: an x-ray plasma source that produces first x-rays; an x-ray optic in optical communication with the x-ray plasma source and that: receives the first x-rays from the x-ray plasma source; focuses the first x-rays to produce second x-rays; and communicates the second x-rays to a sample that produces product x-rays in response to receipt of the second x-rays and second light; and a microcalorimeter array detector in optical communication with the sample and that receives the product x-rays from the sample.