Caleb has an opaque, reflective mineral. It has a blank luster.

Caleb has a mineral that possesses certain visual and physical properties. If the mineral is described as opaque, it means that it does not transmit light; no light passes through it. Regarding reflectivity, if a mineral is reflective, it is capable of bouncing light off its surface, which can give it a shiny or glossy appearance. However, the term "blank luster" isn't a standard term in mineralogy. Normally, luster refers to the way a mineral reflects light, and common terms to describe luster include metallic, vitreous (glassy), pearly, silky, greasy, resinous, waxy, and dull or earthy. Since "blank luster" is not a standard descriptor, it is possible that there might be a misunderstanding or miscommunication regarding the term used. Still, considering the other characteristics, such a mineral could be expected to have a non-metallic luster of some type if it is not shiny like a metal.