A gum resin from the herb Dorema Ammoniacum. This resin solidifies into a tear drop shape and produces an unpleasant aroma. It has medicinal uses dating back to Hippocrates, it is used for respiratory issues (ie bronchitis) and can be used as a stimulant.

"Lying in the single blanket upon the loosely planked floor of the sagging and gloomy cavern acrid with the thin dust of departed hay and faintly ammoniac with that breathless desertion of old stables..."
--LIA (109)