X-ray fluorescence analysis, fused bead, loss on ignition কী?

X-ray fluorescence analysis measures the concentrations of the elements of a solid from the intensities of the characteristic X-rays it emits under an X-ray beam, by comparison with standards of known composition. A fused bead is a glass disc made by melting a weighed rock powder with a weighed flux, such as lithium tetraborate, and casting the melt; it is homogeneous whatever the grains of the powder were. The loss on ignition is the fraction of its mass that a powder loses when heated at a fixed high temperature, mostly water and carbon dioxide driven off.