Marcasite are small, greyish, stones that have a long history in jewellery making – going back to the Incas in South America. They usually have a faceted top and are flat on the back – although I have had them with pointed backs. To call them marcasite is actually incorrect. They are – iron sulfide with cubic crystal structure – usually referred to as iron pyrite. Marcasite – which is related – is too soft to use. It was very popular in Victoria times and was cheaper than diamonds. For a full description of the history of marcasite look on the Gemondo website – gemondo.com/t-marcasite_history.aspx it is very informative.
