Genuine Lapis Lazuli shares the same pigment code as synthetic ultramarine blue. However the two are extremely different in practice. Genuine Lapis has a blue-grey note to it in all but the highest grades, and also reveals yellowing in oils more than we've noticed from regular ultramarine. Lapis may shine better in applications other than oils. However if you want to try it, genuine lapis is offered by Rublev and Michael Harding.
In terms of health and safety, Monona Rossol mentions limits for respirable dust called PNOS limits. Please see her work for more information.
Virgil Elliot's work on Traditional Oil Painting mentions that this color is moderate for how much oil it requires to be made into an oil paint. Some categorize ultramarine as slow drying, while others feel it's closer to the medium side of slow. The natural mineral that lends the blueness is called Lazurite, and the naturally occurring impurities such as calcite (clear) and pyrite (gold) give it some of its complexity and charm.
