Today I was making up some solutions of tin(II) chloride dihydrate (SnCl2.2H2O) and I noticed that an insoluble, yellow chemical had formed at the bottom of the beaker. I have no idea what this could be. I've thought about the possibility that there was an impurity in the tin chloride, but the label on the jar of tin chloride I was using said that the chemical was at least 97% pure (the stuff in the jar was coloured white, so there couldn't have been much of an impurity if there was one). Also, there seemed to be too much of this yellow stuff for it to just be an impurity. So, does anyone have any ideas as to what this yellow chemical is and what may have led to its formation?