Pyrites
/pəˈraɪtiːz/
Definition 1 of 1
Pro Tip 1/3Not Gold
Pyrites resembles gold but is worth much less, hence the nickname 'Fool's gold'. 
He thought he struck it rich, but it was only pyrites, not real gold.
Pro Tip 2/3Creates Sparks
Pyrites can be struck to create sparks for starting fires in survival situations. 
She used pyrites and steel to create sparks and light the campfire.
Pro Tip 3/3Mining Context
Pyrites is often discussed in mining, where differentiating it from valuable minerals is important. 
The miners had to learn how to tell pyrites apart from actual gold veins.