Theurglass, also called glassteel, is a strong and transparent material.
Glassteel lacks the normal greenish tint of glass, gleaming a dullish and almost translucent gray. It is both stronger and half as light as iron.
It is mostly used to build fantastic castles but also finds common use as a hull plating for Spelljammers. Some also use it to create weapons and armour, though for most, the cost of doing this is prohibitively expensive, especially when crafting armour.