I submitted one of mine for testing and they said "The sample is a low melting point fatty substance not a gallstone". well that report stinks of no testing to me because they didn't say what the fatty substances was. Others have had their green stones successfully tested as cholesterol. Next time I get a good lot of stones I'm going to submit for more testing and get my doctor to phone them. She agrees with me that they should at least have an answer for what the fatty material is!!