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Crystallization for Polarized Light Microscopy

I have a passion for microscope, and have over the years started to improve my setup to allow me to capture all manner of things. The most recent addition (June 2016) was the purchase of a polarizing retrofit kit for my Radical RXL-4T Microscope and my Nikon DSLR.

A polarizing microscope is an often undervalued tool which allows the microscopist to control which light reaches the objective based on the polarization of the light. One of the great features of Polarized Light Microscopy is the fantastic color that arises from a number of ‘optically active' samples as a result of double-refraction or Birefringence . This double-refraction occurs because materials in a molecularity ordered compound can be either Isotropic (the index of refraction is equal in all directions) or they can be anisotropy (the spatial distribution of properties is non-uniform, e.g. refraction), it is the non-uniform refraction that creates the fascinating colors.

Whilst I have some chemistry background through university, I am far more biologically inclined so this article is designed to share some of the findings I had around which organic and inorganic materials formed crystals or optically active lattices. Over time I will aim to update this article with links to individual chemicals which had an interesting crystal structure or that were optically active and write-ups on each.


It should be noted that the following experiments were conducted in a chemistry laboratory, with appropriate PPE. Because most if not all of these chemicals are considered toxic, the following should not be repeated except in a controlled and safe environment.


In most cases, I have dissolved the respective chemical in either water or a specific solvent, placed this directly on a microscope slide and through heating attempted to remove the solvent…

Chemical Notes
Calcium Carbonate Did not form crystals
Potassium Permanganate Formed crystals
Copper Acetate Formed crystals
Stannus Chloride Formed crystals
L-Glutamic Acid Formed tree like crystals
Starch Formed bubbles
Sulfur in Carbon Disulphide Formed crystals
Mannitol Formed crystals
Magnesium Chloride Did not form crystals
Potassium Carbonate Formed small crystals
Magnesium Sulphide Formed crystals
Citric Acid Formed crystals
Monosodium Glutamate Did not form crystals
D-Fructose Did not dry under heat
ALS Ferric Formed crystals
Copper Sulfide Formed some crystals
Fructose Did not dry under heat
Quinol Formed crystals
Vitamin B6 Formed crystals
Aluminium Chloride Formed crystals
L-Alinine Formed crystals
Sodium Carbonate Formed crystals
Boric Acid Did not form crystals
Sorbic Acid Formed crystals
Vitamin B (Palminate) Did not form crystals
Tin Chloride Formed crystals
Lithium Chloride Did not form crystals
Lactic Acid Did not form crystals
Acetamide Did not form crystals
Vitamin E Acetate Did not form crystals, did not dry at temperature
Iodine Formed crystals
Sodium Persulphate Formed crystals
Vitimin A Acetate Did not form crystals
Caffeine in Methanol Formed crystals



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