Disclosed is a measurement probe for a measurement of elements in a mineral slurry. The measurement probe includes a housing having an X-ray window. The housing encloses: an X ray source positioned to emit source X-rays at the X-ray window; an X-ray detector positioned to detect X-rays from the X-ray window; and a control module. The control module is configured to: control an operation of the X-ray source and the X-ray detector; process X-rays detected by the X-ray detector to generate X-ray spectra data; and process the X-ray spectra data to determine a quantity of one or more elements of interest in the mineral slurry. The measurement probe further includes a probe mount adapted to couple the measurement probe to a pipe mount on a pipe carrying the mineral slurry; when the probe mount is coupled to the pipe mount, the X-ray window provides a transmission window for X-rays into a lumen of the pipe.