Iceburst stone

Iceburst stone (氷爆石) is a mysterious resource that enables the vertical maneuvering equipment to function. They are found only on Paradis Island.

Characteristics
The caverns found beneath the factory city were once volcanic calderas. As temperatures beneath the earth decreased as volcanic activity ceased, the natural gases within the caverns solidified at high pressures, becoming like icy stones. When exposed to temperatures greater than the freezing temperatures in the caverns where the stones are found, the stones rapidly vaporize. This creates a small, bursting explosion from which these stones get their name.

According to Zeke Yeager, iceburst stones are only found on Paradis Island, deposited there long ago in gigantic holes using the power of the Titans. As a result, they are extremely rare and valuable. The people of Paradis are ignorant of how valuable the stones would be to the world outside. He claims that the mineral can make a struggling nation like Hizuru prosper. However, it is possible Zeke has been misinformed or has gotten iceburst stones confused with the stones found in the Reiss Chapel.

Applications
Due to the practicality of such amounts of gas coming naturally in compact, solid forms, the iceburst stones are used as the source of gas which powers vertical maneuvering equipment. They are placed into canisters made from iron bamboo for storage, and when heated they release the gas necessary to make proper use of the equipment. However, improper treatment or use of the gas yielded from iceburst stones can be fatal.

Trivia

 * The description of iceburst stone and its physical formation bear a striking resemblance to, also known as methane ice.
 * When telling Kiyomi Azumabito about the iceburst stones, Zeke Yeager describes rumors of large deposits of glowing rocks born from the power of the Titans and placed underground in Paradis Island by the "King of the Titans." This exactly matches the description of the rocks found underground beneath the Reiss Chapel, which glow and are said to be made by the "first king" using the power of the Titans. These stones are NOT iceburst stones and the people on Paradis Island are using them as a source of light, not to power the vertical maneuvering equipment.