In the desert, the line between life and death is sharp and quick
“Eyes of Ibad” is the term given to the blue-within-blue eyes of spice addiction. A diet that includes large quantities of spice will make both the iris and the white of the eye turn blue, so that the pupil is surrounded by blue.
It is never explicitly stated in the books, but this document assumes that a higher concentration of spice will result in a deeper blue. Thus, desert fremen, village fremen and city fremen all have eyes of Ibad, but those of a desert fremen will be of a deeper blue than those of village fremen, and those of a city fremen will be the least blue. These differences are obvious to Fremen, and may be visible to an off-worlder if they are paying attention.
At the Baron Harkonnen’s order, a reward of 500,000 solaris has been offered for a crysknife. He wants a crysknife because it, along with the blue-within-blue eyes, identifies the wielder as a fremen, and so having possession of one would open up the possibility of infiltrating a sietch.
Rabban has put a price of 250,000 solaris on the fremen leader known as “Umma”. The conditions of the reward state that Umma must be delivered to Rabban alive.
The Baron Harkonnen does not know about this - Rabban is trying to hide his problems with the fremen, and so doesn’t want his uncle to know that he’s offered this reward. The Harkonnens have heard of a new fremen leader named Umma, but they have no idea who he is, and assume that “Umma” means “leader” (in fact, it means “prophet”). Depending on who tries to claim the reward, Rabban may not actually pay out - he may decide that killing the claimant is cheaper and less likely to lead to inconvenient truths getting back to his uncle.
The Harkonnens are under-reporting the quantity of spice that is produced, allowing them to build up a stockpile of their own. It is essential that this is kept secret, since the Harkonnens would face the wrath of the Emperor and the other Great Houses if it were discovered.
A typical spice mining operation will involve one harvester, one carryall and four spotters. Spice mining operations are not conducted far from the Shield Wall, as storms become more frequent and navigation more difficult. This combination of factors means that casualties in both men and equipment increase dramatically when operations are conducted far from the Shield Wall.
Harvesters are large ground vehicles that harvest the spice from the sand. A typical harvester is around 120m long and 40m wide, with independent sets of wide tracks. They are carried to and from a spice blow by a carryall. They have a crew of three (driver and two journeymen). The harvester’s rhythmic vibrations when operating attract worms, so the crew have to work hard to collect as much spice as possible before being picked up by the carryall. Working on a harvester is dangerous work.
Carryalls are large ornithopters, used to ferry harvesters to and from spice blows. They have a crew of four (2 pilots, 2 journeymen attachers). Because of the tremendous value of the spice, the carryall will pick up the harvester at the last possible moment, allowing the harvester to collect as much as possible of the spice.
Spotters are light ornithopters, with a crew of three (one pilot, two spotters). They fly around the spice blow, watching for wormsign and warning the harvester and carryall of incoming worms. They are adapted for longer range, and are well sealed against dust and sand.
Water is, of course, very scarce. Water sellers sell water for between 20 and 30 solaris per litre. A death still in a fremen sietch can extract around 40 litres of water from a body.