There is another thread about finding small amounts of Marcasite stones for repairing Marcasite jewelry. See
http://www.rings-things.com/cgi-bin....
When you say marcasite I think of point back and flat back stones to set into jewelry. These are usually the mineral pyrite or shiny black glass stones. The quick Google search I did showed that FeS2, Iron Sulfide, occurs in different forms with different properties. Pyrite, or fools gold, has a crystal structure that can be cut and polished. When set in jewelry it is called by the trade name marcasite. The mineral Marcasite is also Iron Sulfide but it is usually only seen as a mineral specimen because it is not sturdy enough for cutting and polishing into stones or beads. If that isn't confusing enough, you can read even more at http://mineral.galleries.com/mineral....tm
In any event, I don't know of any beads made out of Marcasite. We sometime get beads of Pyrite. We also carry Hematite and synthetic Hematine which is a shiny black stone sometimes confused with Marcasite.
All that said, I may have missed the point of your question entirely. :confused: We need some more information about what stone you want and what you want to make.
What type of beads are you looking for?
Are the findings you want set with the stone or are you looking for findings to mount stones in?