Looks like a marcasite nodule to me. I have collected many of these from various locations around the country. Nearly every one has disintegrated into a white powder. The sulfur in marcasite (iron sulfide) combines readily with water vapor and oxygen in the air, especially when the relative humidity is above 60 percent, and forms sulfuric acid, which "eats up" the rest of marcasite nodule. The sulfuric acid reacts with the iron to form iron sulfate, the white powder left behind. The sulfuric acid will also react with the container in which you have the marcasite stored. The sulfuric acid may also become a vapor which can adversely affect the rest of your collection. I always store my marcasite separate from the rest of my collection. I even have a bunch of small marcasite nodules in a mason jar that seem to have lasted longer than the others. I'm fairly positive lacquer won't work, since it is permeable to water vapor. Here is a link to an article that explains how to preserve pyrite fossils from the same affliction. However, I'm not sure it is a process you want to go through just for your marcasite nodule. (http://www.discoveringfossils.co.uk/Pyritetreatment.htm)

Hmm...Maybe if you vacuum-packed it??

Hope this helps,

--Ole Vern

From Ole Vern - June 14, 2008 at 08:10:27

Message: 66619