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How To Test A Stone For Gold

Visual Inspection

gold If you have found a rock that you suspect contains gold, you may have noticed that the rock has some gold-colored specks or streaks business. Before doing any of these tests, take a good look at the stone and ensure you know what to look for.

The first gadget you need to make sure the rock’s surface is relatively clean. Removing loose debris will aid in visual identification and should be done before running the rest of the tests anyway. Real gold is usually confused with pyrite (fool’s gold), and to distinguish between the two, we must be able to see the mineralization correctly.

Real gold can be distinguished from pyrite by the lack of a crystal structure and a more pronounced golden yellow color. Pyrite has a distinct cubic crystal construction, while real gold usually appears smooth and jagged. The color difference can be hard to tell without seeing the gold and pyrite next. Still, pyrite is generally slightly more coppery in color and tarnish compared to real gold’s light gold and silvery yellow.

Visual identification of gold can be difficult, particularly when potential gold occurs as specks in the rock matrix (usually quartz). It may be helpful 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 for any cubic mineralization that suggests pyrite. In most cases, however, further testing should be do.

Measure Weight And Volume.

This quiz is fun! Gold is meaningfully heavier than just about any rock you find it in, especially quartz. In fact, with a thickness of 19.3 g/cm3, it is more than 7 times heavier than quartz and nearly 4 times heavier than pyrite!

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

Volume is a bit more complicated. I like to use my large 2-cup gauging cup. Fill it halfway, then place the stone in the water (assuming it’s small enough for that). The size of the stone can be slow by the amount of water displaced. When the waterline rises 3/4 cup, that’s how big the stone is. You can use Google to convert this volume to cubic centimeters.

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

Because pyrite is about twice as heavy as quartz, it can be difficult to tell if the gold-colored material in your rock is pyrite or quartz, but the denser your rock, the more likely it is to contain gold. The density also depends on the amount of pyrite or gold in the rock. This method is best use in conjunction with other tests on this list.

Magnetism Test For Gold

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

The effectiveness of this test depends quite a bit 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. On the other hand, you may not feel any effect on the magnet and therefore assume it’s real gold when there simply wasn’t enough pyrite to register it.

If you want to test your rock with a magnet, I recommend getting a good quality rare earth magnet from your local hardware store. These magnets are extremely strong and will give you a better indication of whether or not your rock contains pyrite. An ordinary magnet you pull out of your fridge probably isn’t strong enough to track it.

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