When looking for suitable gold-bearing ground in which to prospect for gold, some geological formations can give you hints. Identifying such rocks requires a little practice, but they can make your research much more manageable.
The rocks that have gold in them are quartz, iron, magnetite, pyrite, and Lead. However, not all will contain gold. They only give you better chances of identifying gold-bearing grounds. Analyzing the rocks’ surface, and using topographic maps and geological reports can be useful.
Below you can find a useful guide to identify such rocks and read the landscape better. Let’s dive in.
Table of Contents
Quartz
Gold is usually associated with quartz, but not all quartz formations will contain gold. However, the two elements have a special relationship, which, if understood, gives you better chances of identifying gold deposits and trace a lode.
Generally, quartz is much more common than gold in nature. Therefore, not all quartz deposits will contain gold, or, if they do so, the amount of gold is so minute that mining of that deposit is not profitable.
Quartz consists of silica – also known as Silicon Dioxide – and boasts a hard crystalline structure composed of silicon and oxygen atoms. Silica tends to trap minerals and metals, which, in some cases, might contain gold.
There are several varieties of quartz on the planet, and their appearance can vary from milky to transparent. In terms of color, you might notice types that tend towards a pink tone and others towards a red one.
Quartz “veins” are deposits inside host (or country) rocks. Scientists believe that the formation of both quartz and gold happens in a similar way and at similar temperatures, which cause them to behave similarly[1].
If you notice gold nuggets containing quartz or “floats” (pieces of quartz along a river bed), the lode could be nearby, and prospectors would try to trace back to it[2]. However, when doing so, you should keep into consideration the degree of erosion of the specimen. If a nugget or float boasts smooth surfaces, the chances are that they might have traveled far from the lode. Several “floats” in a location are a better indication of the presence of a lode[3].
Color: white, pink, red, milky – depending on the variety
Composition: silica (Silicon Dioxide) and oxygen atoms
Magnetism: diamagnetic
Specific gravity: 2.65
Magnesium Ferric
While this mineral might not contain gold, it can indicate where to find it. Also known as magnesioferrite, this mineral presents a dark color with red or black strikes on the sides of a formation.
Magnesium Ferric indicated gold’s presence because the two elements are formed in a similar way or at similar temperatures. Unlike gold, this iron oxide mineral is composed of magnesium and ferric iron. Fragments of this rock formation might end up in your pan at the end of the panning process in the form of black sand.
Color: black or dark gray with red tinges
Composition: magnesium and ferric iron
Magnetism: magnetic
Specific gravity: 4.65
Pyrite and Chalcopyrite
Pyrite – also known among prospectors as Fool’s Gold – is likely to be associated with small quantities of gold[4]. However, the two elements boast substantial differences that prospectors should be aware of to avoid misinterpreting their findings.
Pyrite is a common metal that can be found in several locations, even outside of gold deposits. However, if you are on gold-bearing grounds, pyrite’s presence could lead to the discovery of small quantities of gold. This miner’s nickname derives from the fact that it tends to confide prospectors due to its appearance.
Gold and pyrite are associated because they both derive from veins located within magmatic (igneous) rocks, but pyrite can for at low temperatures as well[5]. If you notice a piece of golden metal in your pan, you should check whether this is real gold or just pyrite.
Some differences between the two could be determining. These include the hardness, streak, color, and glittering. Pyrite, being extremely common, is not with much.
Color: golden-yellow but glittery due to the particular crystalline structure
Composition: iron sulfide
Magnetism: magnetism
Specific gravity: 5.10
Iron and Magnetite
Iron and magnetite, as well as hematite, often compose the black sand concentrates visible at the bottom of your pan. These materials have a high specific gravity. Even if they are lighter than gold, sometimes their presence indicates nearby gold sediments.
Magnetite, iron, and Lead and hematite are often created within gold veins. They then become detached from the lode and spread around the deposit. Since these are lighter than gold, they will travel in a different way, so searching nearby locations might be required.
Color: black, dark gray
Composition: iron and oxide of iron. Magnetite is the principal iron ore.
Magnetism: magnetic
Specific gravity: 5.2
Lead
Lead is one of the elements that can truly indicate the presence of gold. Indeed, Lead is characterized by a much higher specific gravity than the surrounding elements and rocks. Therefore, it is likely to follow a similar path of the one through which gold will travel.
Lead can be found in the form of rocks, small accumulations, or sand. Therefore, it is essential to examine the locations surrounding the streambed material, and the black sand concentrates in your pan. Since, like hematite and gold, it is not magnetic, it will remain in the pan when using a magnet.
Color: bluish-white
Composition: naturally occurring element
Magnetism: diamagnetic
Specific gravity: 11.34
Identifying Gold-Bearing Locations
Aside from the types of rocks that you can find near a particular placer, it is essential to examine their appearance. For example, granite tends to be associated with gold in specific locations, but its smooth surfaces will cause the gold particles to slip off it.
Some tips can help you identify the best places when searching for a viable location for your prospecting activity. In the video below, gold prospectors can learn how to read a river to see the best results from their efforts.
Surfaces of the Rocks
As we have seen, rocks and formations with smooth surfaces will let gold particles slip off. Instead, if you have noticed the presence of crevices and cracks on the rocks’ surfaces, it might be worth prospecting in the area[6]. You will be able to find these wither on the sides of the river banks or further towards drylands.
Topographic Maps
The use of topographic maps[7] can help you identify viable locations where you can prospect for gold, especially if you are in a place you are not familiar with. In this case, you might ask the local authorities for maps that have been updated recently, as this can show you viable geological and rock formations in the area.
Geological Reports
Geological reports are an excellent resource if you wish to prospect in a location that is still new to you. Geological reports allow you to understand the history of the place, as well as if it has already been mined or prospected in the past. Of course, heading towards locations where gold has already been found gives you higher chances of identifying new deposits.
Conclusion
Identifying gold-bearing locations can be particularly tricky, especially for beginner prospectors. However, rock and mineral formations, such as pyrite and quartz, indicate where gold could be found.
Other ways of identifying such locations or the presence of such rocks are to acquire the area’s topographic maps and geological reports. They can be acquired through the local authorities. Otherwise, speaking to the local prospectors or prospectors’ club can help you find the best locations.