Here's something funny. All of these slides are from a science fair project in the early 70's. There are 45 samples of various chemicals on microscope slides. It was pretty easy to buy chemicals in those pre-meth days when home chemistry was a good thing. The project was about crystal structures and appearance, both microscopic and macroscopic. Here are six chemicals grown into crystals for the project. Where did the time come from?
CuSO4 is upper right, much more blue than its polarized appearance. Lower-right are two crystals of Alum. one is just Alum while the other is Chrome Alum (violet) on which a layer of Alum was crystallized to show their completely compatible crystal lattices. Alum is KAl(SO4)2 and Chrome Alum is KCr(SO4)2.
Top-center looks like Potassium Dichromate from its color and crystal structure. There is no corresponding microscope slide, but there is an Ammonium Dichromate slide. The structure is similar, and Ammonium Dichromate was a favorite of mine for its excellent volcano demonstrations! Hard to tell which one it is right now.
Top-left is Rochelle Salt that gets a green appearance in some cases; it's probably an impurity but the same green hue is seen in some web photos. It is a piezoelectric crystal; one fellow accurately wrote "I grew a microphone." The other two are as yet unidentified, but lower-left looks like Rochelle Salt as well. It has various macroscopic shapes and there are three Rochelle Salt slides. Bottom-center is completely unknown.
It's amazing how well these lasted over the years! Let's see... 2020 - 1971 = OMG 49 years. The macro crystals were sprayed with Varathane for protection, but the slides just sat in the slide box the whole time - including a very hot and sometimes damp Sacramento garage for many years.
I find it rather fun to put "creative" chemicals under the analyzer. One of the slides is Microdol-X - does anyone remember Microdol in the darkroom? Fertilizers and cleaning products can be interesting, too. Get a pair of polarizing filters and you can do this with whatever microscope you have.