With a water, particulate and fibre mixture, a method of quantifying fibre content may include providing a sample of the mixture, filtering the sample to produce a particulate and fibre mixture, burning the particulate and fibre mixture to produce a fibre sample, and dissolving the fibre sample to produce a fibre solution. The fibre solution may be analyzed to determine an elemental content of the fibre solution. The elemental content may be compared to a known elemental content to estimate the fibre content.