Mithril

The magical imbuement of mercury. Has a slight purple hue, and is almost always seen with a very glossy finish due to its method of creation.
To create an object out of mithril, one starts with mercury set within a mold. Once a body of mercury has been imbued past the transition point, the entire mass locks into place as a single solid and gains its new color. The newly created object has some give/springiness to it, but applying enough force for any part of it to reach its breaking point shatters the entire piece similarly to tempered glass. After shattering, the fragments revert back to liquid mercury.
Note that mithril is perfectly safe to handle due to it forcing itself into a coherent shape at all times. In fact, it is an ideal material to contain precious substances- absolutely none of the container can contaminate the sample. As a result, mithril sees a lot of use in applications requiring a sterile environment and handling. Most typically as a lining within a shock-resistant container to minimize degradation.
Mithril production facilities tend to be kept away from more polite society, as its workers tend to be driven sick or insane.