Umbrim

Umbrim, sometimes called Shadowglass or is a hard, brittle glasslike stone created from the tangible shadow that emanates from all of The Collective's beings. It resembles slate in appearance, but is incredibly smooth and almost frictionless despite its seemingly uneven surface.

The manufacturing of Umbrim is a closely guarded secret and only remains in its form when in proximity to a member of The Collective or their shroud itself. When outside of these conditions, it will revert to the liquid-like tangible shadow, or shroud.

Usage
Umbrim is often used in the construction of Collective buildings and ships, and seems to amplify their user's telepathic powers.

It is also a choice material for assassins around the galaxy, as one can create a simple weapon which would dissipate into nothing in a few hours.