Also Read: Natural Gold Indicators (Part 2)
Gold Geology and the Natural Indicators that can help you find gold
Not all gold deposits out there have been found and mined. There are still places that contain gold that have never been worked, despite the fact that miners have been searching for gold for hundreds of years now. If you can find one of these undiscovered gold deposits you have a good chance that you have found something special, since you will have been the first person to mine it. To find one of these deposits, you need to be able to identify the natural indicators that will lead you to finding the gold.
Learn the Geology of your Mining District
It is extremely important to learn about the geology of your particular mining district. All areas are different, and you need to understand what to look for in the specific area that you are searching for gold. There are certain things that are common to all gold districts, but understanding exactly where and how gold is found in the particular district that you are searching is extremely important.
Productive Rock Types for the Area
When researching a mining district, good gold geology references will indicate the general rock types that area associated with the productive gold mines in the area. Pay attention to these most common rock types and always be looking for them when you are out prospecting. They can be an indicator of where gold will occur.
The general rock type alone is generally not a great indicator or where to search, since it is probably common once you are within a known gold district, but it is one of many things that are worth considering.
Probably just as important to identifying the country rocks associated with gold is being able to identify the host rocks that are generally not associated with gold. If your research has never indicated that gold occurs within a certain rock type, then you certainly don’t want to spend a significant amount of time searching within that type of geology.
Geological Contact Zones
Being able to identify geological contact points is very important (and often completely overlooked) by prospectors for finding areas that gold will occur. Simply put, this is an area where two different rock types come together. Your research will often indicate with rock types are going to be the most productive from a gold prospecting perspective, but the most important thing is that there is a contact. Often the rock types are irrelevant, as gold seems to occur in all different types. What is most important is that some type of contact occurred, which created pressure and often extremely high temperatures which caused fissures to form and gold to be pushed up to the surface.
An entire book could be written on the subject of contact points and gold formations. To keep it simple, I will just say that identifying these areas were different rock types came together are often extremely important.
The general trend of the geology within your district is very important. Look for contact points where different rock types come together at a 90 degree angle. These contacts resulted in high pressure and high temperature conditions that would commonly produce gold. You will find that many of these areas will have some historic workings, there are still areas out there that are “textbook” contact zones that are very rich with gold that have never been mined.
Gold Geology and Ground Color Changes
Color changes in the soil are another indicator of a contact point. Depending on how much bedrock is exposed in an area, you may or may not be able to easily identify contact points where different rock types come together, but you will be able to see where soil color changes. Since the soil is composed of the host rock, even a small change in soil color can be an excellent indicator of a contact zone.
Some color changes can be very readily apparent, while others can be quite subtle. You aren’t looking for small areas with minor change here, you want to try and identify distinct lines of different soil types.
These contact zones may be generally short, but sometimes they will run in a generally straight line for many miles. You may also have success finding new gold bearing areas by locating productive mines and then noting a color change that extends off from the mine. There may be valuable gold deposits in a nearby drainage that are an extension of the same contact zone that occurs at a well-known mine just over the hill.
Remember to always study the different types of gold geology and you will soon learn that there are plenty of areas that have not yet been found.