Science Helps Understand "Ultramarine Sickness"

Two chemists have discovered the reason why the lapis-lazuli-based blue pigment prized by medieval painters fades so drastically over time. Ultramarine, more precious than gold, was often used for portrayals of the robes of the Virgin Mary, and Michelangelo used it in the Sistine Chapel.

Now the chemists are trying to discover a way to keep the rare and beautiful pigment from fading.