Used to classify (or sort) rocks by size. Gold separation works best when the gravel to be worked consists of similar size particles. This allows the material with a higher specific gravity (such as gold) to settle to the bottom without interference from larger, heavier rocks. The larger rocks would also settle to the bottom due to their weight, not their specific gravity. Club members own a large variety of classifiers.
As with gold pans there is a large variety of types, shapes and sizes. The most important difference is the mesh size. This usually ranges from 1/2″ square holes down to a mesh number of 100 with mesh sizes of 1/2″ and 3/8″ being most commonly used in the field. The smaller mesh sizes (bigger mesh numbers) might be used when working with concentrates. The smaller the mesh size used in the field the more likely that gold nuggets will be lost in the discard but larger openings can also cause the loss of gold due to inefficiencies caused by large size differences in the material being worked.
A mesh number indicates the number of openings per linear inch whereas a mesh size quoted in inches or fractions of inches is the actual size of the openings. Thus a mesh number of 2 is the same as 1/2″ mesh and a mesh number of 4 is the same as 1/4″ mesh. A 1/2″ mesh has 2 openings per linear inch which for a square mesh would be 4 openings per square inch. A rectangular mesh would require two measurements to completely specify the size of the openings. The notation (-10+14 mesh) refers to material that will pass through a 10 mesh screen but not through a 14 mesh screen. Be aware that there are other standards that differ, especially British and metric systems.
One of the more popular classifiers is a 14″ diameter model which has a taper to enable it to fit nicely over a standard 5 gallon bucket and will also fit in a 14″ gold pan. It has 1/2″ square holes which are just small enough that a dime will not pass through diagonally. It also stacks nicely with 14″ gold pans for storage.
