Greensand (geology)

Greensand is an interesting type of rock. It's actually made of tiny pieces of the mineral called glauconite. Glauconite is made of iron and other minerals like potassium and magnesium. When these minerals come together and form glauconite, it is dark green and shiny and it often contains fossils and shells. Over time all these tiny pieces of glauconite get squished together and form a rock called greensand. It's a sedimentary rock and can be found in both shallow and deep parts of the ocean as well as in rocky cliffs and other areas. Greensand is often used as a soil conditioner and a fertilizer because it is high in minerals that plants need to grow healthy.