Kirfür-Arbin

Kirfür or Kirfür-Arbin is the rock of the Arbin Watershed. Due to the combination of various influences, including the river system, plant life, and sediment transport, the rocks here possess a unique structure, namely that they are able to fracture very cleanly in one dimension (typically that along which the river runs or makes contact with it). However, in the other two directions, this is cleanliness is forgone for highly irregular and jagged surfaces. This type of rock, being the only such stable rock formation for hundreds of kilometers, is of vital use in the Hýyó-Hayïd and the southern Amoŋot Desert.

Formation

The Kirfür is a metamorphic rock that resides most often along the bank walls of the Arbin River system. Its structure is made of layers are planar sheets running along the plane of the clean fractures. This is due to the river's influence, as the flowing water regularly dispenses and picks up sediments in roughly equal measures. Any sediments that do get stuck are shielded from getting washed away by roughness and random grooves in the rock, which results in a very smooth surface that has been effectively polished by the current. The sediments, initially only resting on the surface, steadily become kneaded into the surface by successively torrents. This is the reason behind its sheer density.

When a rock surface has been fully polished, the river turns again to an erosionary influence, and steadily wears away sediments from the surface. The cycle then restarts, as the sediments collect on the surface and repolish it. This doesn't necessarily result in a stagnant level of rock, but rather is a very gradual process of building up, as the water wears down different parts of the rock in different ways in each iteration of the cycle. As such, the means by which the water causes inconsistencies on the surface can lead to a slightly more effective means of trapping sediment there. Thus, more sediment means more of a buildup there than otherwise would be.

Instead of referring to layers as each successive application of polishing, one usually uses the word to describe a thickness of around 5-10 cm, as this amount of weight is high enough such that the rock layers below it can't quite maintain contact with it without it easily slipping. 5 cm is typical of rock samples far away from the river bank, as these get less sediments from the river and thus are much less dense than those near or inside it.

Harvesting

The Harvest of Kirfür is tricky, as the continuous cycle of wearing down and polishing has no definitive start or end. In addition, the mere act of stepping on a piece of Kirfür has a good possibility of causing wear and tear on an otherwise pristine surface. Rather, the most efficient means is to cause a landslide, mainly by throwing a sharp material upwards and bringing it down with enough force to create a fracture in the rock that extends and splits the rock up to 1-1.5 kilometers around it. The aim of this is never towards the rock that is part of the riverbed proper, but rather the rock right on its edge. This fracture only affects the top layer, and the force is enough to dislodge and break the rest of the rock's contact with it. Without the rest of the rock to keep it steady, the dislodged top layer slides down en masse as according to the slope of the land. The harvesters then run downstream, most often to a spot where the river thins, to collect the pieces.

Applications

The Kirfür rock is used as a rudimentary type of brick and is heavily characteristic of all styles of the Ótaš-Hayïd. Being roughly-edged, it is unable to form airtight structures, but in the context of the Hýyó-Hayïd, this is much to their benefit. This landscape is notorious for its harsh wealther conditions, especially its wind. As such, the use of these bricks forces the existence of openings throughout the walls, which act as a natural source of ventilation and a means to improve structural integrity. However, these bricks do not allow flexibility in orientation that would be required for more complex formations like large oculus-like windows, which would have to be supplied by other types of brick.

In industry, Kirfür has a major use as an effective means of draining and filtering water and other liquids. In this format, multiple pieces of Kirfür are arranged on top of a wire platform above a collection container. There are two types of arrangements. One involves taking multiple pieces of Kirfür that are formed from the same fracture or a single massive piece, which again leads to the same polished look that naturally occurs in the riverbed. The other, which is much harder and requires more training, involves systematically arranging pieces such that the gaps between each piece are so thin as to rival that of the first method. In both methods, the fractures are widened just a bit so as to catch the sediments but not the water, and the surfaces are roughly sanded to render the grooves more pronounced. To filter, a sample of water is poured across the rocks, and the cracks, fractures, and impurities catch the sediments that flow across it. The water is collected at the container and poured again across the rocks. A typical filtration session comprises 20-30 pourings, and the samples of water comprise anywhere from 15 to 300 liters, with the number and size of rocks being adjusted accordingly.