Gold In Quartz Matrix? The 224 Detailed Answer

Panning for gold can be a fun hobby, even though it’s a lot of work! You may be able to harvest gold flakes from rock if it contains gold among its minerals. The safest way to extract gold from rocks at home is to crush the rocks. However, you can use Quicksilver to extract the gold if you can get some, although it’s dangerous. While both mercury and cyanide can be used to extract gold from rock, using them is hazardous to both your health and the environment.[1]

David J. Conner grew up in the jewelry business and is a gold expert. David’s grandfather started the fourth generation family watch and jewelery company in the 1930s. When David’s father took over Orocal in 1965, the family employed 28 watchmakers and expanded into other specialties, including jewelry made from gold quartz, a rare stone found in Alaska that the family understands better than anyone.

What is gold quartz?

Gold bearing quartz is quartz stone with naturally embedded veins of gold. Gold bearing quartz comes in many colors such as yellow, pink, purple, gray and black, but the rarest and most valuable color is white as the contrast with gold is the most pronounced. Quartz containing white gold is considered gem quality or jewelry quality. Many first-time visitors to Alaska have never seen gold quartz before, not only because of its rarity but also because not many jewelers know how to work the stone. Some visitors even wonder if it’s real gold, and yes, it is. In fact, it is one of the rare types of natural gold.

How is gold bearing quartz formed?

Hundreds of millions of years ago, intense heat used hydrothermal pressure to melt the gold and quartz into liquid lava flows up to 3,000 feet below the surface. As the lava flows cooled, the gold and other minerals were crushed by seismic activity and welded to the quartz. Gold remaining in the quartz deposits is referred to as gold-bearing quartz, or gold quartz for short.

Erosion eventually exposed the beautiful veins of pure gold in the quartz. This gold was washed into rivers and streams and in the rushing waters it tumbled and bounced against rocks and sediments, eventually forming gold nuggets (that’s why you can see tiny remnants of quartz in some nuggets). Pieces with high gold concentrations sometimes separated from the quartz as a whole.

Where is gold bearing quartz found?

Gold bearing quartz is found in underground hard rock mines in the same areas where natural gold nuggets are found.

In Alaska, it was first discovered in 1880 in the town of Juneau. Regions in Canada, California, the western United States and Australia are also known for gold bearing quartz.

“When erosion occurs, it turns gold into flakes, so you can find gold quartz anywhere you find gold. Alaska, British Columbia, California and Australia are the only known places where gem quality can be found.” – David J. Conner

Grading of Natural Gold Quartz Like other gemstones, natural gold quartz comes in different grades. Gem quality quartz rock is cut into slabs to expose the veins. These slabs are then hand cut and polished into smooth, beautiful and unique gemstones. Because the gold is naturally randomly embedded within the quartz crystals, each piece is unique. Such gems are rare because the mining locations are kept secret. It took generations for David and his family to gain the miners’ confidence that they could continue to source and supply the highest quality gold bearing quartz on the market. Beware of Imitation “Glacial Gold” or Fake Gold Quartz Because the real mineral is difficult to mine and commands a high price, some manufacturers use a lab-made imitation that resembles the natural stone. Do not be fooled! While some use real gold and cast it in quartz, known as faux gold quartz, others just use gold leaf and mix it into a white resin. This process has very little value. Authenticity So if you want a natural stone, always ask for a certificate of authenticity when purchasing gold nuggets or gold quartz jewelry. Orocal is known for having high quality authentic gold quartz with spectacular gold patterns. Orocal is guaranteed authentic and offers you 110% of your money back if it’s not. They have been PROUDLY making Alaskan style jewelry in the USA for over 50 years. About Orocal Orocal Natural Gold Company specializes in gold found in its true form. Since 1965, Orocal has been a premier source for authentic, high quality gold nugget and gold bearing quartz jewelry. Because gold quartz is difficult to obtain, many jewelers carry low-quality or handcrafted imitations, including fool’s gold or iron pyrite. However, Orocal’s pieces come with a certificate of authenticity. These pieces can make spectacular additions to your collection and make a perfect gift for that special someone in your life.

Gold still encased in quartz, often referred to as a gold sample, is highly sought after by prospectors and collectors alike. Each one is unique and a real treat.

Though rare, it’s still possible to find nice specimens if you know where to look. Here are a few tips that will help you increase your chances of finding one.

Anywhere you would normally find gold has the potential to produce a gold quartz sample, but if you want to specifically target it, certain areas have higher chances of producing one. Do a little research in the area you want to explore and try to find out if the area has ever produced nice specimens in the past.

There are certain mining areas that are known to produce beautiful specimens. I know of one particular area where I’m prospecting that almost all nuggets have at least some quartz matrix and many of them have high quartz content with really attractive gold veins running through it. These are the areas you want to try and find.

Where to look

If you don’t know if an area is known for producing specimens, speak to local miners in the area. You may be willing to share a little knowledge. Go to the library and look for books and geological reports on the area. Often these resources mention such things and can help point you in the right direction.

Once you’ve established a general area in which to work, you need to focus on the specific job you want to seek. Because these specimens are generally rough and unpolished, you should look near the source of gold production and not near the water.

The gold in rivers and streams has been there for millennia and has had time to erode. That’s why most of the gold pieces you find when dredging or sluicing are small, smooth nuggets. Look closer to the source.

What do I mean by close to the source? You want to find the old ore mines where prospectors dug into the hills to pan for gold. These passage mines may be a tunnel leading hundreds of feet into the earth, but often it was small excavations that only scratched the surface of the earth.

150 years have passed since the early prospectors worked these areas, sometimes these small prospects are almost invisible, just a small depression in the slope with a subtle heap of waste material nearby. It may take a trained eye to spot these locations, but when you find one, it can be a gold mine!

Techniques for hunting gold in quartz

So what is the best tool to mine gold in quartz rock?

By far the best chance of finding one of these specimens is to use a metal detector. Since we are looking for quartz boulders with visible gold, a metal detector is the perfect tool. They allow you to scan a very large area, covering a lot of ground.

Search the old tailings, if there are piles of hand-stacked rocks, quickly scan them with your detector. Check the entrance of old mine entrances and waste rock you find. The old-timers tended towards high-quality material, since processing low-grade ore did not pay off. At today’s gold prices, any gold is good gold! Also, with modern metal detector technology, we can “see” more than miners could in the early days.

It’s also worth noting that not all specimens are “collectible”. Sometimes high grade ore will ring out from your metal detector, but the gold is completely encased in rock. If you’re encountering a lot of high-grade ore, you might just want to crush the rock and scavenge out the gold within.

Finding a rock that you believe contains gold is an exciting experience. You may have noticed some gold colored spots or streaks or it is heavier than expected. In any case, once you have found a rock that may contain gold, the next step is to do some testing and verification. Testing a stone for gold is something you don’t do every day, so knowing how to go about it isn’t easy. After going through this process a few times, I decided to put together this guide to help anyone wondering how to test their rock for gold.

To test a stone for gold, first perform non-destructive visual inspection and tests for weight and magnetism. You can also use destructive methods such as testing hardness, streaks, ductility, or pulverizing and panning the powder. You will need a scale, glass, unglazed pottery and a strong magnet.

Each of these methods will give you new information about your stone, which together will tell you fairly definitely whether your stone contains gold. You don’t necessarily have to do every test, but the more you are willing and able to do, the more confidence you can have in the gold content of your rock. I’ll detail the order in which you should take the tests and how to do each one correctly.

Test Type What to look for Visual non-destructive non-cubic mineralization, golden color Hardness destructive gold scratches glass does not streak destructive gold leaves a gold streak Weight non-destructive gold is heavier than other rocks Magnetism non-destructive gold is not attracted to magnets Ductility destructive gold is easy to deform and to cut

How to test a stone for gold

Visual inspection

If you’ve found a rock that you suspect contains gold, it’s probably because you noticed that the rock has some gold-colored spots or streaks. Before doing any of these tests, take a good look at the stone and make sure you know what to look for.

The first thing you should do is make sure the surface of the rock is relatively clean. Removing loose debris will aid in visual identification and should be done prior to performing the rest of the tests anyway. Real gold is most commonly confused with pyrite (fool’s gold) and in order to distinguish between the two we need to be able to see the mineralization properly.

Real gold can be distinguished from pyrite by the lack of a crystal structure and a more pronounced yellow-gold color. Pyrite has a distinct cubic crystal structure, while real gold usually appears smooth and irregular. The color difference can be difficult to tell without seeing gold and pyrite side by side, but pyrite usually appears a bit more brassy and tends to tarnish compared to the bright gold to silver yellow of real gold.

Visual identification of gold can be difficult, particularly when the potential gold presents itself as tiny specks in the rock matrix (usually quartz). It can be useful to have a 10x gem loupe to get a better look at the crystals. I would recommend this one from Amazon which has an LED light and is incredibly affordable.

Hold the stone close to your face and examine each patch with the gem loupe and see if you notice any cubic mineralization that suggests it is pyrite. In most cases, however, further tests must be carried out.

Measure the weight and volume

This test is fun! Gold is significantly heavier than almost any rock you’ll find it in, especially quartz. In fact, with a density of 19.3 g/cm3, it is over 7 times heavier than quartz and almost 4 times heavier than pyrite!

Mineral Density (g/cm3) Gold 19.3 Quartz 2.65 Pyrite 5 Density of gold and associated minerals

What we’re really trying to calculate with this test is the density of the rock. To do this, we need two measurements: weight and volume. Weight is easy enough. I like to use my grocery scale, which is accurate enough to measure weight to the nearest tenth of a gram.

The volume is a little trickier. I like to use my large 2 cup measuring cup. Fill it about half full, then place the stone in the water (assuming it’s small enough for that). The size of the stone can be measured by how much water is displaced. When the waterline moves up 3/4 of a cup, that’s how big the stone is. You can use google to convert this volume to cubic centimeters.

Once you have weight and volume, calculating density is easy. Density is simply weight divided by volume. If the density is at or very close to 2.65 g/cm3 you probably only have a piece of quartz, but if it is significantly heavier there is a good chance the rock contains gold.

Because pyrite is about twice as heavy as quartz, it can be difficult to determine whether the gold-colored material in your rock is pyrite or quartz, but the denser your rock, the greater the likelihood that it contains gold. The density also depends on the amount of pyrite or gold in the rock. This method is best used in conjunction with other tests on this list.

Test for magnetism

Another very simple test you can run on your stone to check for gold content is to check for magnetism. Gold is not magnetic and is not attracted to magnets. Pyrite, on the other hand, is attracted to magnets because of its high iron content.

The effectiveness of this test is quite dependent on the amount of “gold” in your rock. If only traces are present, this test is less reliable because if these “golden” spots are in fact pyrite, there may not be enough of it to show much magnetism. You may not feel any effect on the magnet and therefore assume it is real gold when in reality there simply wasn’t enough pyrite to register it.

If you want to test your rock with a magnet I would recommend getting a good rare earth magnet at your local hardware store. These magnets are extremely strong and will give you a much better indication of whether or not your rock contains pyrite. An ordinary magnet you pull off your fridge probably won’t be strong enough to react to trace amounts of pyrite.

It’s important to remember that a magnetism test will really only tell you whether or not your rock contains pyrite (or another ferrous magnetic mineral). Just because you discover pyrite doesn’t mean your rock doesn’t also contain gold. In fact, pyrite often forms together with gold (we call them “associated minerals”), so not only does the presence of pyrite not negate the possibility of gold, it can actually increase your chances.

Test the hardness

So far all the tests we’ve run have been completely non-destructive, but if you’re still unsure whether your stone contains gold or not, it’s time to get a little more aggressive. One of the simplest and most powerful gold tests you can perform on your stone is its hardness. This test is an application of the Mohs hardness scale, which compares the hardness of different minerals by scratching them against each other.

Gold has a hardness of around 2.5 to 3 (on a scale of 1-10), meaning it is very soft. In contrast, pyrite has a hardness of 6 to 6.5, while quartz (the most common mineral in which gold is found) has a hardness of 7.

To test for gold, you’ll need a piece of glass or a mirror that you’re comfortable scratching. Take your rock and try to find a part of it that has some of the possible gold sticking out at an edge or tip. If you can’t find a suitable spot, you can consider hitting the rock with a hammer to reveal new bits of rock, or skip this test altogether.

Tip: If you don’t have a suitable glass, you can also use a copper penny if necessary. Pyrite and quartz will scratch it, gold will not.

Once you find a suitable spot on the stone to test, rub it in a straight line on the glass for about 2 inches. You are looking for a scratch on the glass. If the glass is scratched by the “gold”, it’s not really gold. Because glass has a hardness of around 5.5, only harder minerals like pyrite and quartz will scratch it. If the glass doesn’t scratch, that’s a good sign – you probably have gold in your stone!

If your glass gets scratched, make sure the scratches are from the “gold” and not the surrounding rock. Look carefully at which parts of the rock are in contact with the glass. It is possible that the surrounding rock matrix also made contact with the glass and left a scratch while the gold left no mark.

Perform a streak test

Strip tests are another common method of mineral identification. When rubbed against a streak plate (unglazed ceramic tile), minerals leave a distinct streak of color that can aid in identification. Gold leaves a distinct yellow streak while pyrite leaves a rather ugly greenish-black streak.

To perform the Schlieren tests you will need a piece of unglazed ceramic tile such as B. the back of a bathroom tile. It is important that the pottery is not glazed as it must be rough and abrasive enough to wear away the mineral being tested.

Just like the hardness test, you need to find an edge or spot on your stone where the “gold” being tested sticks out far enough to rub on the streak plate. Unlike hardness testing, it’s okay if you also rub some matrix rock along the streak plate. Quartz and pyrite are a bit harder than the ceramic and could scratch and gouge it, effectively allowing you to push the stone into the slab to get the “gold” in contact with it.

Rub the stone an inch or two along the stripe board and look at the color of the stripe. If it leaves a really nice yellow gold streak, you’re in business – you’ve probably found real gold! If the streak is a different color – specifically the dark green-black left by pyrite – then you have found pyrite or some other mineral.

Test ductility and steepness

If the potential gold in your rock is in large enough chunks, one of the easiest and most telling ways to test for gold is to see how ductile it is. Real gold is much softer and more malleable than pyrite or other possible minerals like chalcopyrite or biotite.

This test is pretty simple. Find a decent piece of “gold” and see if you can dent or bend it with your fingernail. If it yields to your fingernail, then it’s almost certainly gold. The other potential minerals are much harder and stiffer and won’t deform if you just push in with your fingernail.

Similarly, real gold also exhibits a high degree of sectility. If you’re like me and you’ve never heard this word before, that means it’s easy to cut! If you can find a large enough chunk of the “gold” in your stone (it may be the same one you used your fingernail on), take a steel razor blade or very sharp knife and try to cut into it. If the blade cuts through, you’ve found gold! If not, it’s more likely that you’re dealing with pyrite or some other mineral.

Crush the Rock and Pan the Powder

By far the most destructive test on this list, only attempt this if you are comfortable with having your stone destroyed completely. In this test, all rock is crushed into very small pieces and then essentially washed for gold with the remains.

You need a gold pan, which is fairly cheap and easily available online. You will also need a way to crush and grind the stone. I would recommend starting with a good stone hammer and then progressing to a mortar and pestle. If you are looking for a good stone pick I would recommend the Estwing 22 oz stone pick which I wrote about here.

After grinding the stone into very fine grains, all you have to do is place it in the gold pan and fill it with water. Swirl it around until the material is sorted out. If your stone contains gold, it has settled to the bottom of the pan. Remove the other material and you will be left with the “gold”. You can be even more sure you have gold by checking the dust with a magnet.

Take the stone to an examiner

If all else fails or you are unable to perform any of these tests yourself, you can always take your stone to an examiner. These are professionals who have been specially trained for the job and are able to perform all of these tests and more to tell you all sorts of things about your stone and its gold grade.

Still, I would generally advise against taking your stone to an examiner. In fact, it’s pretty rare to find a rock with significant gold content, even if you’re specifically looking for it. And even if you find a rock with gold in it, the amount it contains probably isn’t worth the cost of hiring an examiner and extracting the gold.

If you’ve done some of the tests I’ve discussed and think your stone contains a decent amount of real gold, it might be worth taking it to a prover. They can give you a better idea of ​​the quality of the gold and the value of your stone. That will tell you if it’s worth going back to where you found your stone, and possibly even making a mining claim.

A note on acid testing

I’ve seen several websites that recommend performing a hardness test on your stone as part of the gold testing process. In my experience, this is not an effective or recommended test. The method I often find prescribed is to dip the stone in vinegar or some other common acid and leave it there for a while. Quartz and pyrite are then said to dissolve or dissolve in the acid, respectively, while gold is completely unaffected.

This method just isn’t scientifically well founded and in my opinion a complete waste of time and money while being potentially dangerous at the same time. Quartz is not reactive to most common acids – in fact, many acids such as vinegar, oxalic acid and hydrochloric acid are often used to clean quartz and remove iron stains. Depending on its exact nature, pyrite may or may not react to the acid. It’s just not worth doing this test on your rocks.

You’ve probably heard the stories – a miner or prospector (or Olsen Twin) thinks he’s gotten rich: gold! Eureka! Unless examined, the gold turns out to be a worthless other mineral. Fooled again by Fool’s Gold. But what are these minerals that mislead us?

There are actually three different minerals that are commonly referred to as “fool’s gold”: pyrite, chalcopyrite or biotite. Of the three, pyrite, also known as iron pyrite, is the most commonly confused with gold because of its luster and yellowish hue.

Sources/Usage: Public Domain. A sample of pyrite and quartz. Iron pyrite, also known as fool’s gold due to its resemblance to gold, is commonly found in quartz veins. Pyrite is an important source of sulfur dioxide, which is used primarily to produce sulfuric acid, an important industrial acid. In fact, the consumption of sulfuric acid is considered one of the best indicators of a country’s industrial development. More sulfuric acid is produced in the United States each year than any other chemical. Visit the USGS Minerals website for more information on sulfur. Sample provided by Carlin Green, USGS. The sample is from Spruce Claim, Washington and is 6.2 cm in size. (Image credit: Carlin Green, USGS. Public domain.)

Pyrite is the most common of the sulfide minerals, meaning it is sulfur based. It is the sulfur that gives it its yellowish color. Meanwhile, the metallic shine comes from the iron. Interestingly, although iron pyrite is the most famous fool’s gold, it can sometimes fool even people who know it as fool’s gold because it may contain real gold in its mineral structure.

Sources/Usage: Public Domain. Visit Media for details. A sample of chalcopyrite from Bingham Canyon, UT (Credit: Scott Horvath, USGS. Public domain.)

Calcopyrite is another type of iron sulfide mineral and is closely related to pyrite. However, where chalcopyrite differs is the presence of copper. In fact, chalcopyrite is one of the most important copper ores and a significant part of the porphyritic copper deposits. USGS assessed porphyritic copper resources as part of its 2014 Global Copper Assessment.

Sources/Usage: Some content may be subject to restrictions. Visit Media for details. A sample of biotite. (By Didier Descouens – Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=7899984)

Biotite breaks with form in that it is not a sulfide mineral at all but is more closely related to mica. It’s not particularly yellowish, but small flakes in river sediment can produce a brilliant flash when light shines on it. This lightning has fooled people panning for gold in creeks.

So now you know, and the next time the Little House on the Prairie kids need to learn a lesson about family values, you’ll know the ending before they do!

Gold is most commonly found mixed with other materials in very small amounts. Experienced gold prospectors rarely look for gold, but rather for rocks and rock formations known to contain gold.

quartz

••• Nastya22/iStock/Getty Images

Gold is most commonly found in quartz rock. If quartz is found in gold bearing areas, it is possible that gold will also be found. Quartz can be found as small rocks in river beds or in large seams on hillsides. Quartz’s white color makes it easy to spot in many environments.

alluvium

••• Achim Prill/iStock/Getty Images

Alluvium is a deposit of eroded materials and sediment collected in an area. As gold and other materials are eroded, water and other forces push the small pieces into stream and river beds and other depressions. Because gold is heavier than most other naturally occurring materials, it settles at the bottom of these deposits.

Pushy Rock

••• johnandersonphoto/iStock/Getty Images

Gold is most commonly found mixed with other materials in very small amounts. Experienced gold prospectors rarely look for gold, but rather for rocks and rock formations known to contain gold.

quartz

••• Nastya22/iStock/Getty Images

Gold is most commonly found in quartz rock. If quartz is found in gold bearing areas, it is possible that gold will also be found. Quartz can be found as small rocks in river beds or in large seams on hillsides. Quartz’s white color makes it easy to spot in many environments.

alluvium

••• Achim Prill/iStock/Getty Images

Alluvium is a deposit of eroded materials and sediment collected in an area. As gold and other materials are eroded, water and other forces push the small pieces into stream and river beds and other depressions. Because gold is heavier than most other naturally occurring materials, it settles at the bottom of these deposits.

Pushy Rock

••• johnandersonphoto/iStock/Getty Images

Back to the articles on stones and minerals

Quartz is our most common mineral. Quartz is made up of the two most abundant chemical elements on earth: oxygen and silicon. Oxygen and silicon atoms combine to form tetrahedrons (three-sided pyramids). These stack into crystals. Billions of tetrahedrons are needed to build even a small crystal. Quartz is an almost pure chemical compound with constant physical properties.

Quartz makes up about 12 percent of the land surface and about 20 percent of the earth’s crust. Most of the remaining crustal rocks are rich in silicate minerals, containing silicon and oxygen, among other elements.

Quartz is divided into two groups; crystalline or visible crystals and cryptocrystalline or occult crystals that require a microscope.

Crystalline Quartz

Crystalline quartz is found as tiny crystal glazes sparkling on a rock surface, as well as shapely crystals weighing tons. Quartz crystals are named after the color of the crystals:

Purple amethyst

Pink – pink – tiny amounts of titanium oxide (rutile) crystals give it the pink color

Clear rock crystal (originally thought to be frozen water)

White Milky Quartz – Tiny bubbles in the crystals give it the milky appearance

Yellow, Brown and Black – Smoky Quartz – natural radiation in the rock causes coloring

Crystalline quartz has a hardness of 7.0, making it suitable as a gemstone.

Crystalline quartz is the most common weather-resistant mineral. This explains its presence as the main component of beach sand. In some parts of the world, beach sand has a thin layer of silica gel on the outside. As a result, the sand squeaks when walked on.

Birds migrating from Canada to warmer climates in the fall take grains of silica sand with them in their harvests. These grains of sand are found in areas where no other sand deposits can be found.

Cryptocrystalline Quartz

Chalcedony or cryptocrystalline quartz does not form visible crystals.

Banded Agate is formed by the precipitation of silicon dioxide from a hot water solution. Tiny amounts of iron and other impurities give it a variety of colors. Most of agate’s vibrant colors (pink, green, blue) are formed by dying gray and white banded agate. Some brown agates are colored by heating. Some agates preserve petrified wood and dinosaur bones. Even the microscopic cells are replaced so that the original tree can be identified or the bone structure of dinosaurs can be studied.

Flint and chert are examples of cryptocrystalline quartz without banding. These are usually found as gray, black, or white nodules in limestone and dolomite. Silica dissolved and precipitated from sponge needles and microscopic plants such as diatoms form flint and chert. For centuries, this material was made into arrowheads and other tools.

Jaspers are usually yellow, orange, and brown due to the presence of iron.

Chrysoprase is colored green due to the presence of nickel.

diatoms

Opal is silicon dioxide with added water. Opal’s rainbow colors are created by layers of tiny globules of opal, which disrupt light in the same way a film of oil floating on water creates colors. Opal is deposited from hot springs or from low temperature water. The largest aggregations of opal are the siliceous skeletons of siliceous organisms such as diatoms and grasses.

Quartz products

silicon

Silicon is used in the steel industry as a component of silicon-steel alloys. Silicon is also used as an alloy in copper, brass and bronze. Silicon is a semiconductor whose resistivity to current flow at room temperature is between that of metals and that of insulators. The conductivity of silicon can be controlled by adding small amounts of impurities called dopants. The ability to control silicon’s electrical properties and its abundance in nature has enabled the development and widespread application of transistors and integrated circuits used in the electronics industry. Silicic acid and silicates are used in the manufacture of glass, glazes, enamels, cement and porcelain and have important individual applications. Quartz glass, a glass made by melting quartz or hydrolyzing silicon tetrachloride, has a low coefficient of expansion and high resistance to most other chemicals. Silica gel is a colorless, porous, amorphous substance. It is made by removing some of the water from a gelatinous precipitate of silica formed by adding hydrochloric acid to a solution of sodium silicate. Silica gel absorbs water and other substances and serves as a drying and decolorizing agent.

Anti-caking powder used in food (check label for silicon dioxide) Coffee creamers use sodium aluminum silicate (feldspar) for the same job!

brick

cement

pottery

Cookers with halogen heating elements

Fiberglass used for insulation and boat construction.

Glass

gems

Halogen lamps (quartz glass)

Oscillators – for radio, clocks etc.

Pyrex heat resistant glass and quartz glassware for

Scientific use

silicon metal

Silicon metal is formed by removing the oxygen from the quartz. Crude silicon metal is grown on a seed crystal in a furnace at 1500¼C. In this way, crystals with a diameter of 15 to 20 cm can be produced. Slices of this crystal are cut, polished and photo-etched to make computer chips and solar cells.

silicone

Silicones connect organic materials such as oil, rubber and plastic with silicon.

Finding a rock that you believe contains gold is an exciting experience. You may have noticed some gold colored spots or streaks or it is heavier than expected. In any case, once you have found a rock that may contain gold, the next step is to do some testing and verification. Testing a stone for gold is something you don’t do every day, so knowing how to go about it isn’t easy. After going through this process a few times, I decided to put together this guide to help anyone wondering how to test their rock for gold.

To test a stone for gold, first perform non-destructive visual inspection and tests for weight and magnetism. You can also use destructive methods such as testing hardness, streaks, ductility, or pulverizing and panning the powder. You will need a scale, glass, unglazed pottery and a strong magnet.

Each of these methods will give you new information about your stone, which together will tell you fairly definitely whether your stone contains gold. You don’t necessarily have to do every test, but the more you are willing and able to do, the more confidence you can have in the gold content of your rock. I’ll detail the order in which you should take the tests and how to do each one correctly.

Test Type What to look for Visual non-destructive non-cubic mineralization, golden color Hardness destructive gold scratches glass does not streak destructive gold leaves a gold streak Weight non-destructive gold is heavier than other rocks Magnetism non-destructive gold is not attracted to magnets Ductility destructive gold is easy to deform and to cut

How to test a stone for gold

Visual inspection

If you’ve found a rock that you suspect contains gold, it’s probably because you noticed that the rock has some gold-colored spots or streaks. Before doing any of these tests, take a good look at the stone and make sure you know what to look for.

The first thing you should do is make sure the surface of the rock is relatively clean. Removing loose debris will aid in visual identification and should be done prior to performing the rest of the tests anyway. Real gold is most commonly confused with pyrite (fool’s gold) and in order to distinguish between the two we need to be able to see the mineralization properly.

Real gold can be distinguished from pyrite by the lack of a crystal structure and a more pronounced yellow-gold color. Pyrite has a distinct cubic crystal structure, while real gold usually appears smooth and irregular. The color difference can be difficult to tell without seeing gold and pyrite side by side, but pyrite usually appears a bit more brassy and tends to tarnish compared to the bright gold to silver yellow of real gold.

Visual identification of gold can be difficult, particularly when the potential gold presents itself as tiny specks in the rock matrix (usually quartz). It can be useful to have a 10x gem loupe to get a better look at the crystals. I would recommend this one from Amazon which has an LED light and is incredibly affordable.

Hold the stone close to your face and examine each patch with the gem loupe and see if you notice any cubic mineralization that suggests it is pyrite. In most cases, however, further tests must be carried out.

Measure the weight and volume

This test is fun! Gold is significantly heavier than almost any rock you’ll find it in, especially quartz. In fact, with a density of 19.3 g/cm3, it is over 7 times heavier than quartz and almost 4 times heavier than pyrite!

Mineral Density (g/cm3) Gold 19.3 Quartz 2.65 Pyrite 5 Density of gold and associated minerals

What we’re really trying to calculate with this test is the density of the rock. To do this, we need two measurements: weight and volume. Weight is easy enough. I like to use my grocery scale, which is accurate enough to measure weight to the nearest tenth of a gram.

The volume is a little trickier. I like to use my large 2 cup measuring cup. Fill it about half full, then place the stone in the water (assuming it’s small enough for that). The size of the stone can be measured by how much water is displaced. When the waterline moves up 3/4 of a cup, that’s how big the stone is. You can use google to convert this volume to cubic centimeters.

Once you have weight and volume, calculating density is easy. Density is simply weight divided by volume. If the density is at or very close to 2.65 g/cm3 you probably only have a piece of quartz, but if it is significantly heavier there is a good chance the rock contains gold.

Because pyrite is about twice as heavy as quartz, it can be difficult to determine whether the gold-colored material in your rock is pyrite or quartz, but the denser your rock, the greater the likelihood that it contains gold. The density also depends on the amount of pyrite or gold in the rock. This method is best used in conjunction with other tests on this list.

Test for magnetism

Another very simple test you can run on your stone to check for gold content is to check for magnetism. Gold is not magnetic and is not attracted to magnets. Pyrite, on the other hand, is attracted to magnets because of its high iron content.

The effectiveness of this test is quite dependent on the amount of “gold” in your rock. If only traces are present, this test is less reliable because if these “golden” spots are in fact pyrite, there may not be enough of it to show much magnetism. You may not feel any effect on the magnet and therefore assume it is real gold when in reality there simply wasn’t enough pyrite to register it.

If you want to test your rock with a magnet I would recommend getting a good rare earth magnet at your local hardware store. These magnets are extremely strong and will give you a much better indication of whether or not your rock contains pyrite. An ordinary magnet you pull off your fridge probably won’t be strong enough to react to trace amounts of pyrite.

It’s important to remember that a magnetism test will really only tell you whether or not your rock contains pyrite (or another ferrous magnetic mineral). Just because you discover pyrite doesn’t mean your rock doesn’t also contain gold. In fact, pyrite often forms together with gold (we call them “associated minerals”), so not only does the presence of pyrite not negate the possibility of gold, it can actually increase your chances.

Test the hardness

So far all the tests we’ve run have been completely non-destructive, but if you’re still unsure whether your stone contains gold or not, it’s time to get a little more aggressive. One of the simplest and most powerful gold tests you can perform on your stone is its hardness. This test is an application of the Mohs hardness scale, which compares the hardness of different minerals by scratching them against each other.

Gold has a hardness of around 2.5 to 3 (on a scale of 1-10), meaning it is very soft. In contrast, pyrite has a hardness of 6 to 6.5, while quartz (the most common mineral in which gold is found) has a hardness of 7.

To test for gold, you’ll need a piece of glass or a mirror that you’re comfortable scratching. Take your rock and try to find a part of it that has some of the possible gold sticking out at an edge or tip. If you can’t find a suitable spot, you can consider hitting the rock with a hammer to reveal new bits of rock, or skip this test altogether.

Tip: If you don’t have a suitable glass, you can also use a copper penny if necessary. Pyrite and quartz will scratch it, gold will not.

Once you find a suitable spot on the stone to test, rub it in a straight line on the glass for about 2 inches. You are looking for a scratch on the glass. If the glass is scratched by the “gold”, it’s not really gold. Because glass has a hardness of around 5.5, only harder minerals like pyrite and quartz will scratch it. If the glass doesn’t scratch, that’s a good sign – you probably have gold in your stone!

If your glass gets scratched, make sure the scratches are from the “gold” and not the surrounding rock. Look carefully at which parts of the rock are in contact with the glass. It is possible that the surrounding rock matrix also made contact with the glass and left a scratch while the gold left no mark.

Perform a streak test

Strip tests are another common method of mineral identification. When rubbed against a streak plate (unglazed ceramic tile), minerals leave a distinct streak of color that can aid in identification. Gold leaves a distinct yellow streak while pyrite leaves a rather ugly greenish-black streak.

To perform the Schlieren tests you will need a piece of unglazed ceramic tile such as B. the back of a bathroom tile. It is important that the pottery is not glazed as it must be rough and abrasive enough to wear away the mineral being tested.

Just like the hardness test, you need to find an edge or spot on your stone where the “gold” being tested sticks out far enough to rub on the streak plate. Unlike hardness testing, it’s okay if you also rub some matrix rock along the streak plate. Quartz and pyrite are a bit harder than the ceramic and could scratch and gouge it, effectively allowing you to push the stone into the slab to get the “gold” in contact with it.

Rub the stone an inch or two along the stripe board and look at the color of the stripe. If it leaves a really nice yellow gold streak, you’re in business – you’ve probably found real gold! If the streak is a different color – specifically the dark green-black left by pyrite – then you have found pyrite or some other mineral.

Test ductility and steepness

If the potential gold in your rock is in large enough chunks, one of the easiest and most telling ways to test for gold is to see how ductile it is. Real gold is much softer and more malleable than pyrite or other possible minerals like chalcopyrite or biotite.

This test is pretty simple. Find a decent piece of “gold” and see if you can dent or bend it with your fingernail. If it yields to your fingernail, then it’s almost certainly gold. The other potential minerals are much harder and stiffer and won’t deform if you just push in with your fingernail.

Similarly, real gold also exhibits a high degree of sectility. If you’re like me and you’ve never heard this word before, that means it’s easy to cut! If you can find a large enough chunk of the “gold” in your stone (it may be the same one you used your fingernail on), take a steel razor blade or very sharp knife and try to cut into it. If the blade cuts through, you’ve found gold! If not, it’s more likely that you’re dealing with pyrite or some other mineral.

Crush the Rock and Pan the Powder

By far the most destructive test on this list, only attempt this if you are comfortable with having your stone destroyed completely. In this test, all rock is crushed into very small pieces and then essentially washed for gold with the remains.

You need a gold pan, which is fairly cheap and easily available online. You will also need a way to crush and grind the stone. I would recommend starting with a good stone hammer and then progressing to a mortar and pestle. If you are looking for a good stone pick I would recommend the Estwing 22 oz stone pick which I wrote about here.

After grinding the stone into very fine grains, all you have to do is place it in the gold pan and fill it with water. Swirl it around until the material is sorted out. If your stone contains gold, it has settled to the bottom of the pan. Remove the other material and you will be left with the “gold”. You can be even more sure you have gold by checking the dust with a magnet.

Take the stone to an examiner

If all else fails or you are unable to perform any of these tests yourself, you can always take your stone to an examiner. These are professionals who have been specially trained for the job and are able to perform all of these tests and more to tell you all sorts of things about your stone and its gold grade.

Still, I would generally advise against taking your stone to an examiner. In fact, it’s pretty rare to find a rock with significant gold content, even if you’re specifically looking for it. And even if you find a rock with gold in it, the amount it contains probably isn’t worth the cost of hiring an examiner and extracting the gold.

If you’ve done some of the tests I’ve discussed and think your stone contains a decent amount of real gold, it might be worth taking it to a prover. They can give you a better idea of ​​the quality of the gold and the value of your stone. That will tell you if it’s worth going back to where you found your stone, and possibly even making a mining claim.

A note on acid testing

I’ve seen several websites that recommend performing a hardness test on your stone as part of the gold testing process. In my experience, this is not an effective or recommended test. The method I often find prescribed is to dip the stone in vinegar or some other common acid and leave it there for a while. Quartz and pyrite are then said to dissolve or dissolve in the acid, respectively, while gold is completely unaffected.

This method just isn’t scientifically well founded and in my opinion a complete waste of time and money while being potentially dangerous at the same time. Quartz is not reactive to most common acids – in fact, many acids such as vinegar, oxalic acid and hydrochloric acid are often used to clean quartz and remove iron stains. Depending on its exact nature, pyrite may or may not react to the acid. It’s just not worth doing this test on your rocks.