Iron bamboo (Before the Fall Manga)

Iron bamboo (黒金竹) is a substance once used to craft military weapons and equipment such as the disposable blades of the vertical maneuvering equipment. During later years, it would be slowly phased out and eventually replaced by ultrahard steel.

Description
While the exact properties of the iron bamboo remain unknown, it is believed that as the bamboo grows it absorbs the metallic elements from the ground and stores it over time; this eventually causes the bamboo to harden and granting it extremely durable properties, especially when compared with other types of iron or steel. Jorge Pikale mentions that despite the texture and feel, the iron bamboo is an actual plant.

Usage
Iron bamboo was seen by the military as a rare and valuable commodity towards making weapons and equipment to use, such as sword blades. Despite it being invaluable, it was only seen as growing naturally near the Industrial City; Xenophon and Jorge explain that only a limited amount was to be harvested at a time due to how scarce it was. Due to how rare and valuable iron bamboo is, many have tried to unlawfully harvest the bamboo for their own needs. This prompted the Military Police to enact several safeguards in an attempt to deter thieves; numerous checkpoints were set up along the outskirts of the Industrial City as well as at the entrance to the forest. Permission must also be given by the head of the Military Police to allow access to the forest.