Common type of Riffle

The average riffle consists of a slab that has been nailed cross ways on the sluice box. This can be as little as a lath or as big as a two by four. In most cases these just consist of a piece of one by two normal lumber.

Zig Zag type of Riffle: The zig zag kind of riffle consists variation of the common riffle and is usually used to break up the material before it goes inside the recovery sluice. It is not however that effective when it comes to catching gold though. When it is utilized the current sweeps from side to side as much as a stream meanders. In most cases the sluice with the zig zag riffle has a bigger slope and this allows the water to travel faster. This has a tendency of swishing the gravel back and forth sideways and is very useful when it comes to breaking up the material that has been lightly cemented without having to do too much hand agitation.

Hungarian type of Riffle: Hungarian riffles are built by screwing a piece of iron bar stock around one inch wider than the riffle to the top of the riffle. In most cases the overhang is located on the down side of the riffle but it can also be on either side. This type of make up causes a good amount of swirling action and helps the fine gold be able to settle in. this kind of riffles used to be used a lot in the dredge or bucket operations during the peak mining periods and a lot of claims were made because of its ability at recovering fine values. One other way of making the Hungarian riffle is by just using angle iron.

Obviously this riffle has its good things and its not so good things. In order for it to function adequately the riffles need to be set very closely together, at a distance of around two inches. It does get a little bit complicated to clean up and they do have a tendency of clogging up and if there is a lot of black sand they tend to fill up with it a lot.

Angle types of Riffles: The angle type of riffle is one of the best known and favourites of the portable dredge prospector and it is very good when it comes to recovering very fine gold. For dredges they are placed closely together and this normally consists of only a few inches apart. The big amounts of water produced by the suction pump maintain the water boiling constantly when over these riffles.

Due to the fact that there is very little classifying of the material scooped up by the suction tube, the closeness of the riffles helps to maintain the bigger rock out of the riffles. Besides this, when these stones bounce on top of the riffles, they bump the material that is being worked and this helps to maintain the sands concentrated in suspension.

Cleaning up in this case is not necessary due to the fact that the sluice of the underwater dredge is quite small and can be turned over and the material that is in it can just be dumped out. There are some types that can be taken apart and this allows you to clean them out really well.