Deep if the leached ore is to be removed by sluicing, 5 ft.
The alluvial extracted, which in the Malay Peninsula and Archipelago carries from 5 to 60 lb of tinstone (or "black tin," as it is termed by Cornish miners) to the cubic yard of gravel, is washed in various simple sluicing appliances, by which the lighter clay, sand and stones are removed and tinstone is left behind comparatively pure, containing usually 65 to 75% of metallic tin (chemically pure tinstone contains 78.7%).
A considerable number of men are engaged in the various states on alluvial fields, in hydraulic sluicing, and dredging is now adopted for the winning of gold in river deposits.
Battery, but the starboard anchor was hung up with a strong tide sluicing down the mole, and the ship was carried some 700 yd.
In more modern times there has been the same excavation of shallow pits, and sluicing, sifting and sorting, by hand labour, the only machinery used being chain pumps made of earthen bowls to remove the water from the deeper pits.