Jones riffle

Jones riffle

[′jōnz ‚rif·əl]
(mining engineering)
An apparatus used to reduce the size of a sample to a desired weight; consists of a hopper which passes samples to a series of open-bottom pockets, each of which divides the sample into two equal parts, and the next pass of each part gives a quarter of the original sample, and so on until the desired sample is obtained.