About the blog: What Things Are Made Of

AMERICA'S GLOBAL DEPENDENCY FOR NEARLY EVERYTHING


The United States relies on imports for dozens of commodities in everyday use. Often enough, that reliance is 100%. In this book I aim to provide awareness of the hidden geology and mineralogy behind common things, and to develop an appreciation for the global resource distribution that underpins our society. While concerns about oil import reliance are in the news every day, our needs for other minerals are comparable and are typically unknown even to technologically aware Americans.





Saturday, March 27, 2010

Fragments of the starry firmament

Early residents of Afghanistan mined the rock lapis lazuli more than 6,000 years ago for jewelry, including the famous gold mask of Tutankhamen. By the 6th Century AD they began to produce the deep blue pigment now known as ultramarine. They used it in cave paintings; its use spread to China and India, and eventually to Europe by about 1100 AD.

Grinding the blue rock, mixing it with waxes and oils, and processing in a lye solution yielded natural ultramarine pigment.

Lapis lazuli’s rarity made for notable expense (greater than gold) in making ultramarine pigment. In European monasteries, highest quality ultramarine was used only on the most important, prestigious artworks, for the robes of Mary and the Christ child. By the 1820s, a synthetic version was devised, and reliance on Afghan sources, the most significant in the world, waned.

The rock lapis lazuli contains multiple minerals, with the blue color coming mostly from two complex sodium-calcium aluminosilicates, lazurite and sodalite.

Even after synthetic dyes became the rage in the 1850s and 1860s, the natural material still served special purposes such as printing postage stamps. Stamp collectors who own blue-tinted U.S. postage stamps from the 1860s (such as the 3¢ ultramarine locomotive in the 1869 pictorial issue) probably have some microscopic bits of Afghan lapis lazuli.

The word ultramarine means “beyond the sea,” whence came lapis to Europe. Pliny the Elder gave the beautiful stone a more admiring description, calling it “a fragment of the starry firmament.”

Photo of polished slab of lapis lazuli, from Wikipedia under the Creative Commons Attribution ShareAlike 3.0 License

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