The Stone That Strikes Fire

Pyrite Is a Common Sulfi de Mineral And a Collector Favorite.

- Bob Jones

If you keep striking a piece of pyrite with a steel hammer, sparks fly and the air is filled with a noxious odor. Perhaps without realizing it, you have discovered the chemical makeup of pyrite: iron (sparks) and sulfur (odor). Tiny bits of iron (Fe) will flash from the heat of friction due to the strike. Sulfur (S) is released at the same time in the form of a gas that has a distinctive “rotten egg” odor.The ancients called it /pyrites lithos—” re stone”.

The Stone that Strikes Fire

Molecules of pyrite are composed of one iron atom and two sulfur atoms. It is the most common of all the sulfides and among the easier ones to identify. It is also a wonderful mineral species to collect because of its fascinating variety of crystal forms, which range from the simplest of cubes to some of the most complex twins and multifaced—as many as 48—crystals! It can form concretions, disks called pyrite “suns”, and other oddities. If you ever decide to collect just one species, you should consider pyrite because of its abundant occurrences and wonderfully varied crystal forms.

Pyrite is found in virtually every rock formation and is particularly abundant in some sulfide mines. Scientists have even found it among the several sulfides produced by the amazing black smoker gushers we have discovered along the boundaries of continental plates, such as those in the Red Sea and Pacific Ocean.

Pyrite forms in the isometric system, which means the simple cube is the basis for its varied crystal forms. Cubes are common, so it is not unusual to see a whole line of simple cubes, ranging in size from the tiniest fraction of an inch to something measuring in inches. At shows, these are o en displayed in a curving line from smallest to largest.