The following is a description of the atmosphere of gas giant planets that is pure speculation on my part. It is speculation based on a possible composition of the lower atmosphere of gas giants. This Ooze Zone I describe is not talked about by any source I have read, but I think it could exist. Exist in real life, or not, it is the heart of this story.
In this story, thanks to HX technology, mankind can build manned ships and unmanned probes that can penetrate deep into the atmospheres of the gas giant planets. (This is something mankind cannot do with early 21st century technology.) Those who choose to make the explorations into these hostile climates have found something surprising and valuable....
The first explorers of gas giants -- the robot probes -- found that the air deep down in the gas giants really does get "thick as soup", and if you go even deeper, it finally does solidify, and this makes gas giant "planet surfaces" very different from rocky planet surfaces we are familiar with.
Unlike what happens on rocky planet surfaces, the air-solid transition takes place in gas giants because of a change in pressure, not a change in chemical composition. On Earth the air-solid transition takes place at the border between the nitrogen-oxygen layer we call "air", and the silicate layer we call "ground." In the gas giants this transition takes place at a pressure change, not a chemical composition change. In gas giants, the chemical composition between air and solid layers stays pretty much the same, but the pressure change is enough to change the mix from air to solid. Above the transition layer, the "air" is a mix of mostly hydrogen and helium, with methane, water and ammonia as the major impurities, and below the transition layer the "rock" is roughly the same mix -- just at a high enough pressure to make it act like a solid.
Between the fluid "air" layer and the "solid" bedrock layer, is the "ooze" layer. This ooze layer exists because this mix of hydrogen, helium, methane, water and ammonia is thixotropic in its solid state -- it acts solid when it stays at rest, but becomes more fluid the more it is sheared -- forced to move around a bit. It's like sticky mud on a path or modeling clay in a person's hands -- the more you push it around, the softer it gets. Turbulence, convection currents and Coriolis effects move air around in a gas giant's atmosphere, and those same forces are trying to move the deeper solid parts, too, but the solid parts don't move. Between the fast moving air layer and the not moving solid layer is a layer of atmosphere which is a mix of oozy mud and solid boulders. The rock solid and the mud are both the same material, so the air changes between these two states easily and constantly. In the upper part of this layer, the air is mostly mud-like. In the lower part it is mostly boulder-like.
The layer below the Ooze Zone is too pressurized to move, and is called the Bedrock Zone -- bedrock, for short. This is not a sharp transition -- the upper layers of bedrock can move, and vigorous cracks from the Ooze Zone routinely bring some motion to the upper layer of bedrock. The big difference between bedrock and the ooze layer above is that the cracks don't happen often, and they "heal" back to solid state quickly.
Likewise, above the Ooze Zone, the atmosphere is constantly in motion, and the motion is fast. There are only occasional places where the air is still long enough to harden into lumps, and these quiet spots are small in size. The top of the Ooze Zone is somewhat arbitrarily defined as the layer at which the lumps are routinely in contact with other lumps, so the motion of the mix slows down and becomes more like that of mud than that of air with snow in it. In this upper part of the ooze layer, wind slows down considerably compared to the layers above the ooze because of the friction that comes from blowing around solid chunks of ooze.
The top of the ooze zone acts like a perpetual fall day where there are constantly leaves floating around and endlessly shuffling in the breeze. If you were to take any particular "leaf" in your hand and squeeze it, the squeezing motion would vaporize it back into air and it would vanish. Conversely, if you were to cup your hands and still the motion of the air, it would solidify into a leaf.
At the bottom of the Ooze Zone the layer is mostly rock-solid, and the motion is large scale rather than small scale. The motion at the bottom is that of continental-size plates grinding against each other as Coriolis forces spin these huge blocks round and round horizontally. Between the huge grinding plates are huge boulders acting like crude ball bearings, and between the plates and boulders are cracks filled with mud acting like crude lubricating oil. The oil and boulders are warmed by the friction, so they try to rise. As the oil and rocks move up, the huge blocks then try to settle more, and their lower surfaces are ground into more boulders and oil. These blocks of the lower Ooze Zone are not strong enough to avoid being moved, so even as they settle, they continue to grind. (The blocks below the Ooze Zone -- those in the Bedrock Zone -- are strong enough to resist the horizontal Coriolis spinning effect, so they remain still, unless they are driven up and down by even slower-moving convection currents comparable to those generating Earth's plate tectonics.)
This grinding and churning of the Ooze Zone has been going on since the gas giant planet was formed, so it has been going on for billions of years now. This churning is primarily a mixing process, but it is also a melting and refreezing process, which means it is also a distilling process -- the melting and refreezing will try to separate out the ooze's constituent minerals into distinct groups. This tendency is counteracted by the general mixing of the grinding and convection, but veins of different materials will be created, and those veins created in the lower part of the zone will survive for long periods when they become part of a solid quiet area.
Some of these veins contain commercially interesting materials. These are materials that are created by freezing and melting Ooze Zone atmosphere millions of times, and concentrating the trace products in veins. Most of the veins are worthless, some are materials that have interesting properties in their native environment, but are not stable at human-compatible temperatures and pressures, and a handful of these veins contain materials that can be brought back into space and remain valuable. The first compound found to be of commercial interest -- and the only one at the time of this story -- is Rubyzin.
Unlike The Ooze Zone, Rubyzin is purely a plot device. It is symbolic of the things that are both surprising and valuable that will be found when mankind explores the interiors of the gas giants. What "real Rubyzin" will be like and do, I have no idea.
Rubyzin is a compound that is iridescent -- it is a sort of mother-of-pearl-on-steroids. The first crystals of Rubyzin brought out where fist-size, and were shown off by Belter scientists who took part in the early atmospheric explorations of Jupiter. Twenty years after those first crystals were brought back, Dr. Jim Naylor discovered that if a finely powdered preparation of Rubyzin were applied to human skin, it would be absorbed by the hair follicles and then the person would grow sparkly hair for a while. If it was applied to a man's face, his beard would grow sparkly for a week, or so. Head hair would grow sparkly for a month, or so, and arm or leg hair for a year, or so. In addition to making hair sparkly as it grew out, the Rubyzin had a mild euphoric effect. The net result: a person wearing Rubyzin looked good to others and felt good about themselves -- they were generally more pleasant people to be around. Once this was discovered, Rubyzin-based skin creams and cosmetics spread throughout the civilized world. The spread was even faster than that of tobacco after it as brought back to Europe by the Columbus expeditions. (Columbus sailed in 1492, and in 1598 tobacco was introduced to Korea by invading Japanese armies.)
Because its importance was recognized as soon as the first Rubyzin cream was invented, Rubyzin mining suffered The Curse of Being Important: the people of Earth decided that Rubyzin mining and distribution should be government controlled, and the government decided that Rubyzin mining should be done "safely and sanely."
Many people were not happy with that series of decisions, and at the time of this story there are a whole lot of people all over the Solar System that want to get a lot more Rubyzin than the government was willing and able to supply.
Finding more Rubyzin is what this story is all about.