The best description of ambergris is to be found in Moby-Dick, Chapter 92, "Ambergris", which you may wish to read. It is an important metaphor for Herman Melville because ambergris is the perfect example of how something sweet-smelling and valuable can emerge out of something horrid and repulsive. In the case of ambergris, that horrid and repulsive place is the bowel of the sperm whale.
Although its name derives from "gray amber" in French, it has nothing in common with ordinary amber, which is hard and yellow and consists of fossilized resin from trees. Ambergris is a soft and waxy secretion of the whale's intestines; it can be gray, yellow, white or a mixture of colors, and is found in pieces weighing commonly a few ounces but which can be up to several hundred pounds.
Although it arises in close proximity to feces, because of its strong and spicy odor, ambergris has been used in perfumes, pastilles, candles, hair-powder and pomades. It is still used in perfumes as a fixative (see the node on perfumery for information on the constituents of perfume), although it has largely been replaced by fixatives derived from coal tar.
Some sources describe ambergris as a product of illness in the whale; Melville blames it on indigestion. However it is now believed that ambergris may serve a useful purpose in protecting the intestines of the sperm whale from the stings or sharp beak of the giant squid, which form the major part of its diet. Ambergris is either extracted from the dead body of the whale (as is recounted in Moby-Dick), or found floating on the sea or washed up on a beach.
The main chemical constituent of ambergris is ambrein, a crystalline alcohol, which has the chemical formula C30H51OH; it is related to cholesterol.
Now that the incorruption of this most fragrant ambergris should be found in the heart of such decay; is this nothing? Bethink thee of that saying of St. Paul in Corinthians, about corruption and incorruption; how that we are sown in dishonor, but raised in glory. (MELVILLE)