Cross-polarized Phenidone melt slide.
A few years back I bought an enlarger from a widow and also gave her some price guidance on what here stuff was worth. Out of gratitude, she gave me all of here husbands darkroom chemicals which included three pounds (!) of Phenidone. Considering how a little phenidone goes a long way, I have enough to make developer for two hundred years.
If you are not familiar with the melt slide technique, some chemicals will yield more interesting results if you melt them rather than dissolve them. Put the powder on a slide, put a cover glass on top and hold the slide with forceps over the flame of a lab alcohol burner. At first the powder will melt and boil and then suddenly "flash" into a sheet under the cover glass. Ventilation with a fan is recommended.
Images made through a microscope. All subject types.