So recently my city has seen a rise in overdoses linked to fentanyl being cut in several drugs. Reading up about the drug it seems like some dealers are selling it off as oxy,or mixing it with heroin or molly. As an occasional MDMA user what would be the best way to test to see if my caps are cut with this horribly potent chemical. So far the only method I see is to use a marquis test and see if there is any hint of yellow-orange in the colour vs the purple-black colour MDMA gives. Also, I sometimes tend to buy pure mdma crystals, is it possible for people to cut these crystals with other drugs such as fentanyl?