I have a reagent bottle with an unknown chemical that came with some other lab gear about 30 years ago, I stumbled on it again when clearing out some old stuff.
It is a standard brown glass Merck of about 250ml size. It has no label and never had any indication of a label and I do not know if it is the original bottle.
The powder is a fine dark free flowing crystalline solid. It is DARK green with a gold iridescent sheen when in bright light, something like a butterfly wing or some anti-forgery inks on banknotes.
Yet if I wet a very small portion it dissolves completely and creates a vivid dark blue solution that dries blue in a thin film. If the crystals dry in a clump they form a smutty dark green gold pasty lump that is reminiscent of the original bulk colour.
I had to hand some potassium permanganate crystals and when I mixed a pinch of the two together and added a drop of water a gas evolved and the colour seemed to be somewhere between the permanganate and the mystery chemical blue when spread on paper. Adding a few drops of acetic acid seemed to have no effect.
Can anyone think of an obvious candidate or some simple experiments that could be used to determine the material?