The spice Melange, also simply known as spice, is an imaginary drug created by writer Frank Herbert in his Dune series. It is a biologically derived substance with a scent reminiscent of cinnamon. Its flavor changes with each taste. Its market value during the reign of Emperor Shaddam IV was 620,000 solaris per decagram. The spice Melange is a byproduct of the life cycle of the sandworm of Arrakis and can only be found on that planet. The larval form of the worm, known as the sand trout, is attracted to water. When a sufficiently large mass forms, the sand trout gather in numbers and encapsulate the water in order to maintain an ecosystem suitable for the adult form, for which water is toxic. Inside the capsule, the larvae begin a chemical reaction to transform the water into a substance that is harmless to adult worms. During this process, a quantity of gas is produced, which ultimately causes the entire mass to erupt to the surface in an explosion of carbon dioxide, water, and Melange. The water rapidly evaporates, leaving behind a vast expanse of dry spice, the characteristic purple stain sought after by spice harvesters. The manual collection of spice is now practiced only by the Fremen, as they are the only ones capable of moving on foot in the desert of Arrakis without attracting the dangerously voracious worms.
Most of the spice is harvested using enormous vehicles called harvesters. A harvester is roughly the shape of a 120-meter long and 40-meter wide cockroach and is equipped with a series of wide, independently moving caterpillar tracks. The machine works by sucking up the surface layer of sand and filtering out the spice mixed with it. In addition to the extraction system, the vehicle also contains a plant for an initial processing of the raw material.
Another key tool in the collection of Melange is the carryall, a greatly enlarged version of an ornithopter, the typical aircraft in use within the empire. The carryall is specifically designed to transport a harvester and serves to position the vehicle over the sandy expanses rich in spice and to retrieve it upon the arrival of a sandworm.
Despite the immense size of the harvester, the collection of Melange is still a dangerous operation, as sandworms are attracted to rhythmic noises, such as those produced by a moving machine, and can sense them from great distances. Each time a harvester goes to work, the arrival of a worm is only a matter of time. In the most remote deserts of Arrakis, there are sandworms large enough to swallow a harvester whole, but even the relatively smaller worms found near the Shield Wall can destroy one and devour it at will. For this reason, a harvester is constantly monitored by no fewer than three ornithopters ready to sound the alarm at the first sign of a worm's approach and to call the carryall. Despite being commonly referred to as spice and being able to be mixed with food, Melange is in every way a drug capable of exerting significant effects on the human body. Like many drugs, however, it also causes a strong addiction. The first sign of such dependence is the pigmentation of a deep blue that the iris takes on, and subsequently also the white part (sclera) of the eye. But the damage can be far worse: withdrawal in a dependent individual guarantees a sure death after a long and painful agony. However, this danger does not overshadow the benefits provided by the spice, which give the substance its great economic value.
