So what would you do if I said, "Look! I got you some gold!" and handed you a chunk of this?
Well, you would look at those lovely well-developed crystal faces, for one. You would maybe bounce it gently on your hand and determine it's hefty but not heavy. You could take out a knife and discover you can't scratch it. If you had a plain white bit of porcelain, you could scrape it along and see that it leaves a mostly-black streak, with maybe a little green or brown tint to it. And if you wanted to make me cry, you could pound it into a pile of black dust with a hammer. Any or all of these tests would leave you shaking your head and saying, "Dana, I'm not a fool. You can't fool me with fool's gold! Especially not on April Fools' Day."
And then if I told you that there is gold in it, but it's invisible, you would laugh in my face because it is April Fools' Day, so I will wait until next week to tell you that there's invisible gold in there. Well, maybe not in that particular sample, but we can find some that definitely does have invisible gold in it.
But maybe I tried to trick you with this sample, which looks a lot more like gold, but is still pyrite.
Did that one fool you? Don't feel bad! Perfectly smart and famous people have been fooled by fool's gold, especially back before we had pocket gem and mineral guides that would help us tell the difference. Let's talk about some famous fools fooled by fool's gold for April Fools' Day! (You can use that phrase as today's tongue-twister, too!)
Our first fooled person is Sir Martin Frobisher, an intrepid English privateer (legal pirate, arrgh) who did the first mining in Canada. He got really excited by a sparkly black rock he found on Kodlunarn Island during his first voyage to the New World. He got other people excited, too, and they gave him money for another voyage. He returned to Canada in 1577 and basically opened the first Canadian mine operated by a European, shipping back two hundred tons of ore. His sparkly rocks got the Queen's attention, and she sent him back in 1578 with lots of her money so he could get even more ore. He shipped back 1,400 tonnes of it that July and August. Shipwrecks claimed some of his cargo, but the rest made it to the smelters in Dartford. Alas, it turned out that his lovely "black ore" was just amphibolite and pyroxenite, with biotite, pyrite, and mica making it all sparkly.
In his defense, samples of his ore discovered and tested did have some gold in them: 5-14 parts per billion. And the rocks did make very nice road gravel.
Imagine having to trade nice stuff for a bunch of sparkly sand because your captain is convinced there's gold in it. Sigh. Captain John Smith pretty this "gold" was no such thing, but Captain Christopher Newport was all fired up about it, just certain there was gold to be found, and the colonists at Jamestown were all gold-mad, so there he was, rowing up the Potamac, going to Aquila Creek, and buying a bunch of sand from the Patawomeke tribe. They called the stuff matchqueon, and were probably overjoyed that they were getting quality goods in exchange for it. Smith described it as "a clay sand so mingled with yellow spangles as if it had been half pindust." Yes, sand that's full of stuff that looks like discarded filings from pin manufacturing probably didn't excite him over-much, but I'll bet is was pretty - I've seen sands full of sparkly pyrite flakes, and it was enchanting. I doubt Smith was feeling super-enchanted as he hauled a bunch of it back down the river, but Captain Newport was probably full of sparkly happiness until the 1,100 tons of it he brought back to England turned out to be sediment filled with pyrite. Whoops.
Jacques Cartier was a Breton explorer of the New World. While nosing round the harbor of St. Croix on the St. Lawrence River in Canada (then New France), he discovered what he believed were some lovely gold and diamonds. His judgement may have been affected by the fact that his failure to find the shiny and valuable stuff on his first voyage to New France got his royal support yanked, and he was only here on this voyage because he'd talked a nobleman, Jean-François de la Rocque de Roberval, into funding him. He happily brought his baubles back to France, where he discovered they were merely common quartz and pyrite. Alas!
Then there's that poor bugger who appeared in a Scientific American article from August 1872. I will reproduce it here, as the scan is extremely hard to read:
Fool's Gold and How we may Know It.
The following story is going the rounds of the papers, and would be decidedly rich if it were only true:
A verdant looking Vermonter appeared at the office of a chemist with a large bundle in a yellow bandana, and opening it exclaimed: "There, doctor, look at that." "Well," said the doctor, "I see it." "What do you call that, doctor?" "I call it iron pyrite." "What, isn't that gold?" "No," said the doctor, and putting some over the fire, it evaporated up the chimney. "Well," said the poor fellow with a woebegone look, "there's a widder woman up in our town has a whole hill of it, sad I've been and married her!"
That the poor fellow had married the widow for the sake of the hill of pyrites is very probably true, but that the pyrites evaporated up the chimney is simply impossible, and such a statement is to be regretted because the inexperienced may be led to believe that, if a bright, yellow metallic looking mineral does not evaporate when strongly heated, it must be gold. There are several minerals which are sometimes mistaken for gold, but the two which are most apt to give rise to deception in this matter are pyrites and mica, and hence they are sometimes called fool's gold. The method of distinguishing between them and gold is very simple, and requires no complicated apparatus. Gold is malleable, that is, it can be beated out into thin leaves under the hammer, while the other crumble to powder. Moreover, gold is easily cut with a knife, while if we attempt to cut pyrite it breaks up, and mica separates into thin flakes. It is when mica is fine powder, however, that it most resembles gold, and in such cases, its weight betrays it character. Gold is nearly twice as heavy as lead, and, even by poising it in the hand, we can tell that lead is much heavier than mica.
That's one of the earliest uses of the term "fool's gold," by the way, and right in our very own Scientific American. How awesome is that?
So now you can tell the difference between real gold and fool's gold. Next week, we shall see that the fools who fell for it were not actually so foolish after all!
Halpern, J. (1951): "Frobisher's False El Dorado [Baffin Island - Arctic]." Emeritus Faculty Author Gallery, Paper 56. University of Massachusetts, Amherst.
Hogarth, D. and Loop, J. (1986): "Precious Metals in Martin Frobisher's 'Black Ores' from Frobisher Bay, Northwest Territories." Canadian Mineralogist, Vol. 24, pp. 259-263.
Rickard, David (2015): Pyrite: A Natural History of Fool's Gold. New York, NY: Oxford University Press.