How Do You Identify Pyrite (Fool's Gold)?
Nobody wants to go through the embarrassment of declaring that they have found gold when really they have found fool’s gold… nobody wants to be the fool.
<This article contains Amazon links because a girl needs to eat. You can always close your eyes when you get to that bit.>
This short but effective guide will teach you how to tell the difference between the iron pyrites and real gold. We also want to run through some of the other golden mineral possibilities to make sure that we leave you enlightened.
How To Tell If You Have Found Real Gold or Fool’s Gold?
There is one very quick way to tell the difference between real gold and iron pyrite and that is by applying pressure to it. Poke it with something. Preferably a pin because, let’s face it, gold samples found in the UK tend to be of a smaller size.
The Poke-It-With-Pin Test for Pyrite or Gold
Gold is malleable, meaning it is a reasonably soft mineral. When you apply pressure to gold, it bends. When you apply pressure to iron pyrite it does not bend. Iron pyrite is brittle. Rather than bend, it will break first.
The Streak Test for Pyrite or Gold
To perform a streak test, you have to find a piece of unglazed porcelain from somewhere in your home. The ring on the bottom of some mugs is unglazed. Otherwise, the most common way to find unglazed porcelain is to lift the lid off the back of your toilet and flip it upside down.
Next, take the mineral specimen and try to draw a mark on the porcelain. The resultant mark left behind is the mineral’s ‘streak’.
Iron pyrite will streak a sort of greenish black colour. Gold will always streak golden.
You can also go and buy unglazed ceramic discs or squares. These are pocket-sized, making them ideal for geological field work. You can pick streak testing kits up on Amazon in both the UK and on Amazon USA. You can also buy an expert mohs hardness testing kit if you want to splurge.
The Weight Test
Iron Pyrite (FeS2) is about four times lighter than a chunk of gold of similar size. If you are very scientifically minded (I am not) then you might want to conduct a test to find out what the specific gravity of your mystery mineral is.
Specific Gravity Testing for Iron Pyrite
Iron pyrite will have a specific gravity of between 4.95 and 5.10. By comparison, gold’s density changes based on the carat value. 18K gold is between 14.8 and 16.12.
To perform a specific gravity test, weigh the mineral specimen when it is dry, then when it is submerged in water. Divide the dry weight by the wet weight. Each mineral corresponds to different numbers.
Specific gravity is a good way to identify minerals which have already been faceted.
Not All Fake Gold is Iron Pyrite
Of course, just because you can rule out pyrite does not mean that your mineral specimen is definitely gold. There are other minerals which can fool you with their golden shimmer.
Other Golden Minerals Include:
Mica and Mica Schist. Mica is typically very light and flakes of it can float on water.
Rutile can appear as golden straight lines or threads running through quartz. A gold in quartz habit looks more like the bronchial passage on the inside of your lung than a straight line. Unless, of course, you have mined out a gold seam, in which case well done. No further notes for you. Keep panning.
Goldstone is a man made glass which glitters when you move it around in the light. The glass is infused with different minerals to give it a shimmer. Goldstone might be golden or a variety of colours. It will look like glitter.
Chalcopyrite, bornite, and other peacock ores can produce a golden colour. Often, if you treat these with a light acid (like a clear vinegar) they may change colour.
Arsenopyrite, pyrrhotite, and other related minerals. Most of these can be eliminated with a streak test.
Make sure to check out our previous article about how to identify gold for further information.
I leave you with these words of wisdom: gold is nonmagnetic. If you can use a magnet on it, then it is likely fake.
Comments