Average gravity of some metals

• Mica: 2.3
• Feldspar: 2.5
• Quartz: 2.7
• Calcite: 2.7
• Hornblende: 3.2
• Garnet: 3.5
• Topaz: 3.5
• Corundum: 4.0
• Magnetite: 5.2
• Silver: 7.5
• Lead: 11.3
• Gold: 19.2

Because of the fact that it is insoluble, the finest particles of gold are preserved and since gold is so malleable it will get hammed down into different shapes because of the stones that bang into it as it tumbles along the stream. However, it does not weld itself together and turn into bigger nuggets. Pieces of gold might break down but this will happen from another piece. It has been shown that the biggest pieces of gold come from lodes and not from placers. The rounder and flatter the nuggets are that you find probably mean they have been in the stream for a longer amount of time and have been knocked around more than the ones that come in the crystalline form. Crystalline nuggets are courser gold that has most likely not traveled as much from its original source. The gold that can be found in older placers is regularly finer than those that have their source close by and this is probably because of the alloy silver has been removed by the action of the water. When there is a good amount of gold in a placer deposit it is the result of very opportune circumstances. This occurs in places where there is an extensive amount of mineralization, quick rock decay, and properly developed stream patterns. When all these come together at the same time, large gold placers have the opportunity of being formed.

The process that occurs is simple; in places where the gold has been deposited, the power of the stream is strong enough to carry off the pieces of gold that had settled. The richness of a deposit depends completely on the transporting power and if the bedrock is able to hold onto the gold that has deposited, and obviously how the gold sources does in the stream. When a stream is wearing away at the materials, these materials are constantly being moved downstream. When this type of movement takes place, the water sorts it and this causes more of a concentration of the heavier elements. Disposition then occurs in the stream when the speed goes down, which can occur due to changes in volume or grade. After this occurs, the gold rests with other sediments. In some cases the gold gets trapped inside the bedrock. Bedrock is when the floor of a stream is actual rock. When the gravel gets covered with certain materials such as volcanic material, the stream will flow over this new floor or bed and makes deposits on what is known as false bedrock. This is one of the reasons why there are certain areas that might have more than one layers of gravel with gold in it. One simple way of noticing how a stream lays down these various layers is to look at areas where road cuts have uncovered old stream deposits as well as in canyons where the benches can be noticed. When there is hard and smooth bedrock it is not the best place for a placer deposit. The bedrocks that have the best formations are those that have cracks and crevices and those that are much decomposed, because these are the ones that are easily able to catch onto the gold.