Wet panning
Wet Panning - a Field estimation of Heavy Minerals (R. Fitzpatrick, Uni. Adelaide)
Wet panning of soils to identify, estimate amounts and extract/sample heavy-minerals is an ancient, but still very relevant and effective prospecting technique. The heavy-mineral concentrate (HMC) can be examined in the field to identify and estimate the amount of heavy-mineral grains such as magnetite, ilmenite, zirconium, rutile, monazite and cassiterite. Wet panning is carried out using a flat bottomed, metal or plastic "gold pan" or round bottomed hardwood "dulang", similar to the Malaysian tin pan (British Geological Survey, 2001). The gold pan is generally steep sided, which is commonly riffled so as to retain the densest heavy minerals (Figures 1 to 3).
Place about five handfuls of soil into a shallow pan with an ample amount of water by slowly submerging the shallow pan into a large bucket or basin of water (Figure 1).
Start the wet panning process by shaking the soil vigorously to promote settling of the heaviest minerals at the bottom of the pan. Panning is accomplished using a near-circular swirling motion, first pushing the pan away and then bringing it back to draw the water into the front of the pan as shown in Figure 2). As the water enters the pan it sweeps around the pile of soil on the forward stroke as shown in Figure 2, removing the uppermost and lightest minerals from the top and discharging them into the larger bucket or basin as the water is expelled from the front of the pan as shown in Figure 3. Panning is carried out when the water is deep enough to allow the full pan to sink.
At regular intervals, especially during the early stages of the panning, shake the remaining soil vigorously to encourage the denser / heavier grains to settle to the base.
Continue careful panning and shaking until the required final volume is only about 1 cm in height. Examine the heavy-mineral concentrate (Figure 3) with the naked eye and with a hand lens to identify the heavy minerals and estimate the total abundance (or even their specific abundances using a magnet to estimate the amount of magnetite and/or ilmenite etc.).
Reference
British Geological Survey 2001. Mineral exploration methods in Britain: Panned-concentrate drainage sampling