Arlescium was a mineral mined on the planet Kircone in the Deep Core. In its natural state it was a dark grey ore, soft and malleable to the point where it could be molded in the hands. However, it could be combined with other metals to create an extremely light alloy that rivaled bes'kar in durability. There were two variants of arlescium alloy:
- Amrik alloy, not as light or durable as klas but still on par with any other major alloy, used in the hulls of ships and other large projects. It was relatively easy to make in large quantities, and contained many of the same metals used in the forging of durasteel. Amrik shared the dark grey coloration of the original metal.
- Klas alloy, which was lightsaber resistant and extremely light. It was difficult to make and forge, extremely expensive, but worth the investment for someone who had the credits and knew of its existence. It was midnight blue in color and was lightsaber resistant. Klas was used to make weapons, and was also used in the reactor vessels of the Tilani's antimatter reactors and other high-stress ship components. There is at least one documented use of it as a shell in a cybernetic limb, and some use of it in jewelery due to its rare color. While amrik could be smelted by anyone with the proper skills and equipment, klas could only be forged by a Tilani metalsmith.