Shandon

Shandon was the Realms name for natrolite.

Description
This mineral was found in thin crystals that produced tiny faceted gems often used to adorn clothing. Using many shandons, a skilled clothier could weave them into a veil or a robe, giving it a sheen like beads of water on a spider's web. Because of their size and lack of color, top price was most likely to be had from those gem cutters and dealers familiar with their artistic value. A typical specimen had a base value of 100 gp.

Powers
If an item of clothing had at least seven shandon gems attached to it, then one of the gems could be enchanted with the ironguard spell which gave the garment a permanent ironguard effect that protected the parts of the body covered by the magic apparel. Like the spell, any poisons on the non-magical metal could still be introduced into the body, but no harm would come from metal passing through the garment or the body parts protected by it. The spell effect was canceled if the enchanted gem was crushed, shattered, or separated from the garment.