Iron pyrites

Iron pyrites is an iron sulphide. Its lustre and pale yellow colour makes it resemble gold, hence its nickname 'fool's gold'. I can imagine many a gold rusher unearthing some iron pyrites and prematurely calling 'eureka'.

Iron pyrites is usually found in quartz veins in sedimentary or metamorphic rock. Its crystals are generally cubic and striated.

The rock in my photo shows iron pyrites' small striated crystals and tiny crystals of quartz. If you put iron pyrites in your search engine of choice you will see some spectacular examples
. 
Thanks for hosting McCaviti.