Pyrite, The gold of fools!

I wanted to write about some crazy mineral that no one has ever heard of, but then I realized that no one really cares about minerals they have never heard of. Truth be told, I'm guessing that most people don’t care much about minerals they HAVE heard of. As we sit and think on this little catch-22, let’s take a moment and look at the shiny little blob known as Pyrite.


(That's the scientific picture of pyrite. I think. Or possibly some sort of virus.)

Pyrite is everywhere. Well, nearly everywhere. It’s likely to be anywhere you can find sulfur and iron, which is most places if you spend a lot of time underground or at some sort of sulfur and iron factory. Which to my knowledge don't exist. If you looked really REALLY close at pyrite, you would see a single atom of iron that has totally hooked up with a pair of hot atoms of sulfur, resulting in a steamy, HBO-style chemical formula of FeS2. You would think that this would mean that pyrite is 33% iron and 66% sulfur, but it isn’t. It’s actually 46.6% iron and 53.4% sulfur. I’m not here to explain why this is. You will just have to trust me.

*BEGIN FUN FACT*

Minerals that contain sulfur are known as sulfides! Neat! All your favorites are here! Pyrite, Galena, Realgar, and others. you don't really care.

*END FUN FACT*

Let’s take a look at the little guy in question.

As you can see, it is very shiny. But in geology we don’t call rocks shiny because that would imply that you are having fun with science. In geology anything that looks like pyrite is referred to as having a “metallic” luster. For some reason the term “metallic” reminds me of Robocop, a movie that I saw for the first time the other day. Anyway, you can think on the subject for yourselves and decide what “metallic” reminds you of. But don't tell me what you come up with because I don't care. Here’s a picture of Robocop holding some pyrite.

As the above pictures also show (the pictures above the Robocop one), pyrite comes in a variety of shapes. You’ve got a bunch of little squares, a neat little Frisbee shaped thing, and a blob. But most commonly pyrite likes to show up as the first one. Pyrite likes to show up as a cube.

That’s a picture of what a cube looks like. Drawing 3-D things is fun. Spain is famous for its perfect cubic pyrite cubes. And why not? Look at these things!

Pyrite also likes to show up as something called a pyritohedron. It’s like a cube, but wayyyy harder to draw. Let’s give it a go.

That’s actually pretty close. Anyway, who needs drawings when you have real-life stuff? Here’s what a pyritohedron looks like in the real (internet) world.

Now, some of you may notice that piece isn’t really “metallic” anymore. Like all of us, pyrite is not long for this world. Too quickly the ravages of life take their toll upon the pyrite cube and work to turn it into something else. In this case the pyrite has weathered into a mineral called Limonite. In short, it has simply rusted. Like my Honda.

A fun little note about weathering pyrite is that it often forms a weak acid, which likes to find its way into the groundwater. Here's something special for the nerds! A chemical explination of how pyrite is actively trying to kill you!

4) FeS2 + 15/4 O2 + 7/2 H2O --> 2H2SO4 + Fe(OH)3 4

Ahh, the beautiful simplicity of chemistry! The problem is with that nasty little H2SO4 guy. This guy is known as sulfuric acid, and it's an environmental pain in the butt. Anyway, it gets into the water and makes all sorts of problems.

Finally, pyrite also likes to show up as an octahedron.

Here is what it would look like if it was under attack by a tank and two army guys.

And here’s what it would look like if it were a super villain.

Anyway, those are the three most common forms of pyrite. Sometimes pyrite shows up in a mixture of these forms, and sometimes as none of the above. But I’m not going to draw anymore.

So, now that we know what it looks like, let’s list some facts about it that I’ve found in a book here. It appears that pyrite is pretty hard, clocking in with a hardness of 6! That means that it can scratch glass if you really work at it for a while. Also that means that you can’t scratch it with a knife. These are good things to know if you ever fall into some sort of pyrite-based ninja clan.

Pyrite is perhaps better known as “Fools Gold” because it looks like gold to fools. I think it looks a lot like gold, but I wouldn’t ever admit it because I don’t need people thinking I’m a fool. I hate everyone so much. Anyway, if you ever find yourself with a block of shiny, gold-colored mineral and need to figure out if it is gold or if you are a fool, then here’s what you do.

If at the end of step #3 you have nothing but a pile of gold colored chunks that stink like rotten eggs, then you were likely dealing with pyrite and are, in fact, a fool. If the gold deforms but doesn’t shatter under the blow of the hammer, then you are looking at the good stuff and probably should go try to find more of it.

So, why did pyrite get two names? "Fools Gold" seems scientific enough for me. But, as usual, insults have no place in science. “Pyrite” means “Fire” in greekish, a name earned by the fact that pyrite will send out a neat shower of sparks if you hit it with a hammer. I should have probably mentioned that in the “how to tell gold from pyrite” section of this post. Ah well, everyone loves surprises.

So what is it good for? Other than starting fires when people hit it with hammers and contaminating groundwater when it weathers, the answer may shock and amaze you. Pyrite isn’t really good for anything. Well, other than as a test to see if you are in the presence of fools I guess. Some countries use it as an iron ore, but it stuff produces so much sulfur it isn’t really a preferred source. So I suppose it falls under the large list of rocks that are best used as paperweights, doorstops, crude weapons, and the like.

As I said at the beginning of this post, pyrite is all over the place. Above us, below us, and all around us. Well, probably not so much above us. And only slightly less rarely around us. Mostly it's below us. It most often forms in pre-existing rocks that have been metamorphosed by magmatic intrusion, but it can really show up just about anywhere. Quite often it shows up with minerals that ARE useful to us, such as gold, silver, copper, and whatever else you could ever want. So this guy...

will keep his eyes open for the stuff. Because I strive to only bring you the most accurate and crudely drawn information, let's take a look at these easy to understand stick-figure drawings of how pyrite forms as a result of magmatic intrusion thingies.

The general idea behind those pictures are that lava squishes into the rocks and sends boiling hot earth-waters into the surrounding areas. This water usually contains a ton of crazy minerals that form all sorts of things, including pyrite.

And that is Pyrite. Kinda. Well more or less.