Post by tomcasper745 on Apr 12, 2018 12:47:15 GMT -8
Geology and Contact Zones
You need to learn the geology of your particular mining area. There are some natural gold indicators that can be found in most major gold producing areas, but each area can be different. You should learn to spot the types of rock that are associated with gold in your area.
Gold is difficult to find, but learning about the types of rock that it is generally associated with (as well as the types that it is not associated with) will help you find the best areas to focus your efforts.
Contact zones (also called a dykes or intrusion) are places where two major rock types come together. This is a natural geological process that happened millions of years ago. These events would result in rapid heating and cooling, and this often created the conditions needed for gold to form.
Learning to identify the zones can be difficult, but it is something that will become more apparent as you learn to look for it. There are certain rock types that are better from a gold mining perspective.
3 important rock types worth noting are granite, schist, and gneiss. I have found these 3 types of rock to be present in most of the places where I have found gold.
When these geological masses would contact each other, pressure and high temperatures would cause fissures that would result in gold formation. Gold would be pushed to the surface, making it accessible to prospectors without needing to tunnel deep into the ground.
Identifying the general direction of the geology in your mining area is important. In most of the western U.S., the mountains range in a general northwest-southeast trend. Look for contact areas where some other rock type enters at a different trend to the general geological mass. Many of the richest gold bearing areas will have a intrusions that are at a 90 degree trend to the prevailing geology.
While granite, schist, and gneiss are usually the main rock types, that isn’t always the case. It can potentially be any combination of rocks, although they usually make up at least one of them at gold-rich contact zones.
Geology Dyke for Gold Mining
This roadcut exposed a great example of a contact zone (dyke, intrusion, etc.) where a newer rock pushed up through an older existing rock type. Sometimes gold forms in these locations if the conditions are right.
The color changes of soil are also good indicators of a contact point. Sometimes the major source of bedrock has eroded away long ago leaving behind only soil. You may spot a band of reddish soil, indicating an iron rich intrusion that once existed. The host rock has eroded away, but the red soil (and potentially gold) still remains.
The ground changes can be obvious or subtle depending on their size or the difference in color. Ground cover from grass and trees can also hide them. Sometimes the type of plants growing in the different soil types can help you find them.
Contact zones can be as short as a few feet in length, or they can run for miles and miles. In the California Mother Lode for example, you can look at a map and see major gold mines that seem to line up perfectly in a straight line over miles and miles. They have located contact zones with gold.
You need to learn the geology of your particular mining area. There are some natural gold indicators that can be found in most major gold producing areas, but each area can be different. You should learn to spot the types of rock that are associated with gold in your area.
Gold is difficult to find, but learning about the types of rock that it is generally associated with (as well as the types that it is not associated with) will help you find the best areas to focus your efforts.
Contact zones (also called a dykes or intrusion) are places where two major rock types come together. This is a natural geological process that happened millions of years ago. These events would result in rapid heating and cooling, and this often created the conditions needed for gold to form.
Learning to identify the zones can be difficult, but it is something that will become more apparent as you learn to look for it. There are certain rock types that are better from a gold mining perspective.
3 important rock types worth noting are granite, schist, and gneiss. I have found these 3 types of rock to be present in most of the places where I have found gold.
When these geological masses would contact each other, pressure and high temperatures would cause fissures that would result in gold formation. Gold would be pushed to the surface, making it accessible to prospectors without needing to tunnel deep into the ground.
Identifying the general direction of the geology in your mining area is important. In most of the western U.S., the mountains range in a general northwest-southeast trend. Look for contact areas where some other rock type enters at a different trend to the general geological mass. Many of the richest gold bearing areas will have a intrusions that are at a 90 degree trend to the prevailing geology.
While granite, schist, and gneiss are usually the main rock types, that isn’t always the case. It can potentially be any combination of rocks, although they usually make up at least one of them at gold-rich contact zones.
Geology Dyke for Gold Mining
This roadcut exposed a great example of a contact zone (dyke, intrusion, etc.) where a newer rock pushed up through an older existing rock type. Sometimes gold forms in these locations if the conditions are right.
The color changes of soil are also good indicators of a contact point. Sometimes the major source of bedrock has eroded away long ago leaving behind only soil. You may spot a band of reddish soil, indicating an iron rich intrusion that once existed. The host rock has eroded away, but the red soil (and potentially gold) still remains.
The ground changes can be obvious or subtle depending on their size or the difference in color. Ground cover from grass and trees can also hide them. Sometimes the type of plants growing in the different soil types can help you find them.
Contact zones can be as short as a few feet in length, or they can run for miles and miles. In the California Mother Lode for example, you can look at a map and see major gold mines that seem to line up perfectly in a straight line over miles and miles. They have located contact zones with gold.