A method of manufacturing a standard grain sample for subsequent use in spectroscopic instruments is disclosed, the method comprising substantially permanently fixing the position of each grain within the sample. The preferred method involves filling a mould (10) with grain (12), adding a matrix material (18) to said filled mould, allowing or causing the grain/matrix mixture to harden. The sample (14) is then released from the mould and sawn into blocks (20) which are then used to standardise instruments with calibration transfer, or used as diagnostic check samples.
