https://www.youtube.com/watch?v=7VCDitdIJAM
more from Clare Daly TD http://www.claredaly.ie/
About Pyrite: The mineral pyrite, or iron pyrite, is an iron sulfide with the formula FeS2. This mineral’s metallic luster and pale brass-yellow hue have earned it the nickname fool’s gold because of its superficial resemblance to gold. The color has also led to the nicknames brass, brazzle and Brazil, primarily used to refer to pyrite found in coal. Building stone containing pyrite tends to stain brown as the pyrite oxidizes. This problem appears to be significantly worse if any marcasite is also present. The presence of pyrite in the aggregate used to make concrete can lead to severe deterioration as the pyrite oxidizes.
http://en.wikipedia.org/wiki/Pyrite