transparent substance
translucent substance

In such cases we can see that no transparent substance conducts electricity.

There was ivory in it, and some transparent crystalline substance.

He then took a mysterious transparent substance, out of which he created human souls.

The tiny blind eye exuded a transparent substance and she sipped at it like a bee.

But his crystalline "nervous system" rested on a very hard transparent substance.

There are transparent substances that can conduct electricity.

He touched his mouth to the hard surface of the transparent substance and drew back with startled speed.

Others had large ground-floor windows made of some clear, transparent substance that reflected the light.

A transparent substance that transmitted and reflected light when light existed around it.

Presumably, the glass (or whatever the transparent substance was) diffused the light without absorbing it.