One of his pupils found that adding iodine to the urine of a dog that had been fed quinine produced unusual green crystals.

[2] In the 1930s, Ferdinand Bernauer [de] invented a process to grow single herapathite crystals large enough to be sandwiched between two sheets of glass to create a polarizing filter; these were sold under brand name "Bernotar" by Carl Zeiss.

Herapathite can be formed by precipitation by dissolving quinine sulfate in acetic acid and adding iodine tincture.

[3] Herapathite's dichroic properties came to the attention of Sir David Brewster, and were later used by Edwin H. Land in 1929 to construct the first type of Polaroid sheet polarizer.

Structurally, herapathite consists of quinine (in a cationic doubly-protonated ammonium form), sulfate counterions, and triiodide units, all as a hydrate.