Prospecting Mine Dumps

Another place that is a good prospect for sampling besides placers and lodes are old mine dumps. Modern technology and different procedures for testing might show something the original miners did not see in the first place. One of the best methods for sampling mine dumps is through the pit method. Because of the make up of almost all mine dumps, the material will not stand the sides of a hole at a lot of depth therefore you will need to timber a prospect hole or run some kind of casing.

After the samples have been obtained, it will need to be put together in one area and it should be exposed to least possible amount of contamination with the surface material if you can. In most cases it is put together on a large piece of canvas. The ideal thing to use would be a big piece of metal however these are not usually available when it is time to separate a sample.

If the sample has been obtained from somewhat of a small area such as from the face of a vein, the canvas can be placed close to the work and you can put the sample right on it.

After you have put together the sample material you will need to bring it down or reduce it to as even a size as you can. When placer gravel is being tested for gold values only, more reduction in amount is not normally needed and the sample gets divided up and panned. If you have gotten the sample by cutting it out of rock you will in most cases have to break up the rock into smaller pieces before dividing it up. This is done on the principle that if a very rich piece of big ore gets its way into the last sample the size is very important in providing a false reading. To make it understandable, if you have a piece of quartz that is quite a few inches in diameter and that is speckled with fifty percent of natural gold it could definitely give a false value if it survived the procedure to get into a one pound assay test. 

When field testing is involved or for an assay the material will need to be more crushed before it can be split into the right sample size, unless it is made up entirely of material that is less than one inch in diameter. One of the most practical ways of breaking a rock down is by using a maul or you can also use a small sledge hammer. If you are concerned about little pieces flying all over the place when the rock is broken, you can use an iron ring to contain the samples inside. Iron rings can normally be obtained in metal supply shops as well as in some junk yards.

After you have been able to break down the material to the right size you will need to pile it on the canvas or a tarpaulin so that it can get divided up. This can be done in a couple different ways and it mainly depends on how much material is being divided up. Either a canvas or a tarpaulin is a good way of doing so; however, do not change from one to the other when you are in the middle of dividing it all up.