The claimed particle classifier is utilized to separate precious metals from alluviums in placer mining. The plurality of curved bars functions as riffles to entrap heavy precious metals and conduct the said heavy precious metals into the slit and consequently into the plurality of small troughs located beneath the slit. The claimed particle classifier is operated along with a flow of stream water, which deposits particles and sediment into the slit and the plurality of small troughs. The claimed particle classifier may be operated along with a flow of water from any source other than streams.