Wait That's Interesting

Had it wrong, it's yyttrium.Skynet says;

An intact mantle emits low levels of radiation, mainly alpha particles, which are stopped by the mantle itself, air, or even the outer layer of your skin. The greater concern is dust. If a mantle is damaged, burned, or crumbles, inhaling or ingesting thorium-containing dust is more hazardous than simply being near the mantle. Modern mantles are typically thorium-free, using materials such as yttrium instead.