When searching for gold, knowing what rocks are likely to contain it is a crucial part of the process. Knowing which types of rock will be a good source can help you narrow down your search and increase your chances of success.
One type of rock that is prone to containing gold is quartz. Quartz often forms in cracks and other small openings within rocks.
1. Weight
Gold is one of the heaviest metals in nature. It has a density of 19.3 grams per cubic centimeter, which is more than 15 times as heavy as water!
The weight of rocks that contain gold can be easily determined by weighing them alongside other rock materials. This is important to know because it can help you decide whether a rock contains gold or not.
For example, if you find a hunk of quartz that is significantly heavier than you expected it to be, then it might have gold in it! This method of estimating the weight of gold in a rock is simple and can be done using a set of scales, which can either be digital or beam balance.
If you’re not sure if the hunk of quartz in your rock is gold, you can try weighing it against other minerals and see how it compares. Some of the most common rocks that are similar in weight include quart (density of 2.65 grams), calcite, fluorite, graphite, and halite.
However, if you want to be sure that your rock is actually gold, you can use a gem loupe to look at the individual flecks of gold within the quartz matrix. If the flecks of gold are tiny, then it may be hard to distinguish from other mineral such as pyrite.
2. Hardness
The hardness of a rock depends on the bonds that hold atoms together in crystal structures. If you scratch one mineral, the resulting furrow represents the breaking of millions of these bonds on a microscopic scale.
A mineral’s hardness is measured relative to a standard scale called the Mohs scale, which is composed of ten minerals known for their hardness. To determine the hardness of a mineral, compare its ability to be scratched by softer materials or by steel tools.
Some common objects that can be used for this test include a fingernail, a copper coin, a steel penny, a knife blade, window glass, the steel of a needle, and a streak plate (an unglazed black or white porcelain surface). Once you’ve determined the hardness of the rock, it’s time to take it a step further.
The hardest gold-bearing rocks are quartz. The density of quartz is about 2.65 g/cm3 (on a scale of 1-10).
3. Scratching
During an itch, the skin’s sensory receptors send signals to the brain that cause an itchy feeling. When you scratch, the friction breaks off a few of these receptors and temporarily blocks the itch sensation.
When the same friction sloughs off more cells, however, it triggers more itch signals in the brain. This can be a vicious cycle, because the more the body scratches, the more pain it feels.
In some cases, the itch is caused by a benign invader. For example, a sunburn or psoriasis may send an itch signal to the brain that causes the body to release serotonin, which creates feelings of happiness.
If you are looking at a rock that contains gold, a simple test to determine whether it is real gold or iron pyrite, also called fool’s gold, is to see if it can be pressed with a fingernail or knife blade. If it is, you’ve probably found gold and not fool’s gold!
Another easy test is to rub a piece of the mineral against an unglazed streak plate (an inch or two along the edge). If it leaves a yellowish-goldish streak, it’s likely gold. If it leaves a greenish-black streak, you’ve most likely got pyrite.
4. Denting
Denting is a very easy way to identify rocks that contain gold. This is because real gold is malleable and ductile, meaning that it can be curved or bent by pressure. Other minerals or non-gold metals are much harder and won’t bend when you press them with your fingernail.
You can also test for the presence of gold by putting a pin in it and seeing if it breaks or fractures. If it does break or fracture, then it is probably not real gold and could be a mineral like pyrite.
However, if it does not break or fracture then it is likely to be true gold. If you are unsure, it is also possible to place the rock in corrosive nitric acid and see if it tarnishes.
Another easy and non-destructive way to determine if the rock you’re testing contains gold is by using the Mohs hardness scale. Scratch the rock against a hard surface to measure its hardness and compare it to other minerals.
The Legend of the Lost Gold of Dents Run is an interesting story that has made its way into the media spotlight in 2019. According to a Federal affidavit, Jacob Archer, of the FBI’s Philadelphia art crime team, wrote that he has probable cause to believe that a significant cache of gold is secreted in a cave in Pennsylvania.
5. Sectility
When you find a rock that looks like it could contain gold, you should do a few tests to help decide if it is really gold. The first one you want to do is test the sectility of the rock.
This is a good indicator of how easily it can be broken with a knife. If the rock is brittle, then it will break into angular fragments when you cut it.
However, if the mineral is malleable, it can be hammered into thin sheets (copper and gold) or cut with a knife into fine shavings. It can also be sectile, a property of metals where the valence electrons are not shared between specific pairs or groups of atoms, but flow freely between them instead.
The next one is ductile, a property of copper and gold where they can be bent or twisted without breaking and then staying bent once pressure is released. These properties can be helpful in telling pyrite (“fool’s gold”) from gold.
Finally, there is the cleavage that shows up when you cut a mineral. This is the most pronounced and important feature of all because it can show you what kind of mineral the rock is.
6. Magnetism
The magnetic properties of a rock can tell you a lot about its composition. It can also help you determine whether or not the rock is gold-rich.
Magnetism is a type of force that is caused by the movement of electrical charges or the orbital motions of electrons in an atom’s nucleus. It can take many forms, from the movement of electrons in an electric current to the orbital and spin motions of elementary particles that have a property called “spin.”
When the electrons in an atom line up in their orbital levels, they form a symmetrical tetrahedron. The electrons always have one or more wave centers that are off their nodes, and the constant repositioning of these wave centers leads to the spin of the electron.
This spin can be influenced by the number of unpaired electrons in an atom’s nucleus, and the amount of energy that the unpaired electrons have. This can create a net magnetic dipole in the material.
Generally, rocks that contain gold will be magnetic, and they will also be attracted to magnets. However, the type of magnetism that you will detect will depend on the amount of pyrite and other iron-based minerals that are present within your rock.
7. Glass
Gold can be found in a variety of minerals and rocks, from obsidian to quartz. The most common form of gold-bearing rock is auriferous quartz, which consists of tiny crystals that are embedded in the matrix of a rock.
This mineral is commonly found in the Earth’s crust and was formed during geologic time. As it oxidizes, it can become rich in precious metals such as gold and silver.
It is also used to produce a wide range of glass colors. Some of the most popular include “Rubino oro” (gold ruby), “cranberry,” and “purple of cassius.”
These colors are produced by adding a small amount of gold chloride to clear molten glass, which then undergoes re-heating. The result is a beautiful range of red and pink hues.
Often a small amount of tin is added as well. This compound of tin and gold chloride, called “Cassius purple,” produces a lovely ruby color in this glass.
Gold ruby glass is a fascinating example of how the human imagination can combine science and art to create truly unique objects. It is a testament to the creativity of the Renaissance craftsmen who fashioned these beautiful vessels.