One of the most obvious places to prospect for gold is in quartz veins. Professional prospectors recommend searching for quartz veins, especially for beginners who are yet to learn how to read the ground for signs of gold.
Gold forms inside quartz during volcanic activities and earthquakes, events that cause cracks to form towards the earth’s surface. Water from the water table and steam from the magma fill these cracks, carrying gold and other minerals. The water then condenses, forming the quartz vein.
In this article, I’ll discuss the relationship between the occurrence of quartz and the presence of gold. I’ll also give tips on the signs to look for when searching for quartz veins containing the precious mineral.
Natural Formation
The 1840 – 1857 California gold rush is closely linked to the presence of quartz veins in the Sierra mountains. Initially, miners focused on the surface gold, which was plentiful. However, in 1852, production declined, and the miners started to dig deeper, upon which they discovered quartz veins.
Gold Hill Mine in Nevada became the first quartz mine in California. The natural formation of gold inside quartz is best explained following the series of volcanic eruptions in the area.
The Process
Before I lay out the process, please note that quartz — a crystalline mineral mainly made of silica — and gold melt at very high temperatures. Quartz melts at 4046°F (2230°C) and gold at 4892°F (2700°C). Quartz crystallizes at 1598°F (870°C), while gold solidifies at 1945°F (1063°C).
- During volcanic activities, molten rock (magma) rises toward the earth’s surface. It forms magma chambers that keep filling with magma over a long period.
- As magma collects in the chamber, the earth’s surface above rises, causing the earth to form cracks that widen during earthquakes.
- Over time, the magma erupts through some of the cracks to form a volcano.
- The magma contains water, which contains melted minerals.
- The water fills the crack and condenses. If there are more earthquakes and tremors, the cracks widen, and more water fills the cracks and condenses. During this process, gold and other minerals are trapped in the cracks.
- Sometimes, the water has no cracks to fill, so it flows down and forms alluvial gold.
The Relationship Between Quartz and Gold Deposits
Erosion and earthquakes cause the rocks to break and move, which is why you’ll find broken or displaced quartz veins in areas beyond where volcanic eruptions occurred. Hydrothermal fluids deposit minerals in the cracks in a highly disorganized manner, sometimes at different times.
There are also instances when the fluids don’t deposit minerals. This is why some prospectors sometimes fail to find any metals and minerals in quartz.
Those who strike gold may find it scattered along the vein instead of being concentrated in one area.
Oregon is one of the States with the largest varieties of quartz in the world. It also has mines in Baker and Grant Counties. These discoveries can easily be linked to the 1781 – 1791 Mount Hood eruptive period that formed quartz veins that contained gold deposits.
The other locations with Quartz gold include Arizona and parts of California.
Some prospectors sometimes follow the path followed by alluvial gold, hoping to strike big when they find the gold-rich quartz veins. Fortunately, quartz doesn’t weather as fast as most host rocks.
If prospectors don’t get to the vein fast enough, it’ll eventually wear down, and the mineral will be buried next to the vein or washed downhill into the river. You can use your metal detector around these areas to find precious metals.
The Appearance
Quartz crystals contain several minerals. Since the quartz veins are clear, you see spots of different colors, depending on the minerals present. Gold quartz veins are also unique. There are several signs you can look for to identify them.
Quartz deposits with gold have gold veins or blobs in different areas. Gold deposits are not always obvious, especially if the particles are scattered or too small. It’s harder to spot them in colored quartz than in clear crystals. The mineral can also be confused with pyrite.
If you find quartz rocks in a gold-rich area, you’ll most likely find some with gold. This is probably the surest way to confirm you have valuable quartz. You can also carry out additional tests, such as a weight test, to confirm if the quartz has the precious mineral.
This video shows how to identify gold-carrying quartz rocks.
Confirmatory Tests
If you have quartz rocks and can’t tell if they’re valuable, you can carry out tests to ascertain whether there’s valuable mineral hidden inside the quartz stones. You may think some of the blobs and veins are gold, only to discover they are pyrite.
These are some of the tests you can carry out to confirm the actual content:
Weight Test
A quartz rock that contains gold will be heavier than one without. Get a quartz rock that seems to have gold, and get another rock of a similar size that doesn’t seem to have the mineral. If the rock is slightly heavier, you’ve most likely gotten lucky.
You can also compare rocks with yellow stains. If they’re of a similar size but one is at least 1.5 times lighter, then one rock contains pyrite while the heavier one has gold.
If the quartz rocks weigh almost the same, it can be hard to tell whether or not they contain valuable minerals. This will depend on the average weight of the other rocks that you think contain gold.
Magnet Test
If you need confirmation regarding what minerals the quartz rock contains, you can perform the magnet test. You’ll need a strong magnet because your fridge magnets may be too weak for this test.
If the magnet sticks to the rock, you’re probably dealing with pyrite, as real gold is not magnetic.
Scratch Test
The scratch test will only work if you have a colored corner on the quartz rock. If you do, try scratching a piece of glass. If it scratches, the yellow blobs are probably pyrite. Gold is too soft to scratch, while pyrite is hard.
Streak Test
Just like the scratch test, you can perform a streak test on unglazed ceramic. If the streak is yellow, then you have gold in the quartz. However, if the streak is greenish-black, you’re dealing with pyrite.
Still, it’s important to point out that the two minerals may occur together.
So, while gold may not be present in that corner, it may be hidden in other parts of the quartz rock. You should consider holding on to quartz rocks with pyrite until you’re sure they have no value.
Acid Test
You can also perform an acid test. However, this method will destroy the quartz, so you should be sure you don’t need the quartz before performing this test. You can use vinegar for this test. However, it’ll take a while for the quartz crystal to dissolve.
Hydrofluoric acid is more effective. However, it’s a dangerous acid, so you must be careful when handling it.
When the quartz dissolves, you’ll be left with a few crystals. Fortunately, acid doesn’t affect real gold, but other minerals will be affected.
Extraction
If you’ve confirmed the presence of gold in quartz, the next step is to isolate it. Even if you’re still unsure, you can still break the rock to find out what minerals are hidden in the veins.
- Place the quartz rock in a large pan, preferably a flat one. This will help ensure you lose none of the rock powder.
- Use a geological hammer to break the quartz.
- See if you can collect larger pieces of gold by hand or using tweezers.
- Soak the other broken rocks in the water and pan them as you would when extracting gold.
- Pan and re-pan until you only have dense rocks and metals, including rock.
Conclusion
Gold is a rare metal, but it’s easier to find it in quartz veins. Unfortunately, not all quartz crystals contain this precious metal. You’ll need to check the veins for signs that the quartz rock has it.
Old mines tend to have quartz rocks. However, you need to carry out some of the tests I mentioned earlier to confirm the presence of gold.
