Pigments of My Imagination

I got sidetracked by vacation and few other things and lost my way regarding the chemical elements. The following inorganic pigments are mostly familiar.

Red is for red and white lead in striped lighthouses and also miniature manuscripts. The red color comes from lead tetroxide and the stark white comes from lead carbonate. Both pigments are impervious to the elements which is precisely why Michael Faraday chose them to coat Britain's lighthouses.
Red is also for Barn Red. Farmers in Europe started this tradition by adding ground up rust to the linseed oil they used to protect their barns and sheds (the iron inhibits mold).

Orange is for terracotta roof tiles: The color comes mainly from iron oxides.

Yellow is for yellow school buses.  Originally the pigment came from lead chromate (the color comes from the chromate, not the lead). It too was impervious to the elements. Lead chromate is no longer used to paint buses, but the traditional color stuck with us.

Green is for emeralds. Beryl and emerald are essentially the same material, viz., Be₃Al₂Si₆O₁₈. The only difference is that emerald also contains about 2% chromium, the source of its green color. Chromium also makes rubies red, and sapphires blue.  How does the same element do that?

Blue is for the Prussian Blue. I wrote about this back here. Gun bluing, a form of metal passivation, is another iron coating in disguise. Blue is also for cobalt blue.  As the saying goes: if it's blue, it's cobalt (II).

Indigo is for itself. Its color is challenged by some as a separate distinct color: link The most vivid indigo colors I ever saw were solvated electrons trapped as either sodium electride or as sodium benzophenone. What do electrons really look like? link

Violet is for purple permanganate, KMnO₄ which is actually pinkish purple but I couldn't think of a better example. Can you?

Electrons Have Consequences

The valence electrons of lithium and beryllium metal are spherically shaped and easily lost. Once lost, the remaining two electrons revert back to being helium-like electrons except that the kernel, being laden with more charge than helium, sucks in the remaining two even closer. This explains the extremely small sizes of both Li⁺ and Be²⁺ and ultimately why lithium is such an effective battery material and why even tinier beryllium is found in many brilliant gemstones.

Things change dramatically when we move on to boron, a favorite element of mine. The electrons actually reach out further and take shapes.

Beryllium Is A Sweet Precious Gift

Different variations of beryl, including 1. golden beryl crystal, 2. heliodore. 3. emerald, 4. aquamarine, 5. morganite

The root word of beryllium is old and familiar and lurks beneath the surface of the commonly used word brilliant:

brilliant
1680s, from Fr. brilliant "sparkling, shining" prp. of briller "to shine" (16c.), from It. brillare "sparkle, whirl," perhaps from V.L. *berillare "to shine like a beryl," from berillus "beryl, precious stone," from L. beryllus (see beryl). In reference to diamonds (1680s) it means a flat-topped cut invented 17c. by Venetian cutter Vincenzo Peruzzi.

Beryl and emeralds were known to Pliny the Elder nearly 2000 years ago and he first observed a physical similarity between the two. In the Middle Ages, transparent, colorless beryl was used to make optical lenses, whence the German word Brille which today still means eyeglasses. The invention and manufacture of actual glass spectacles developed in Italy in the 13th century and improvements followed closely with the development of optics.

The minerologist R.-J. Haüy also observed the remarkable similarity between beryl and emerald (hardness and density), and he persuaded the pre-eminent chemist/pharmacist of his time (late 18th century) Louis Vauquelin (of Paris) to analyze the stones to see if they were chemically alike. In 1798, Vauquelin showed that both minerals contained not only alumina and silica as had previously been known, but also a new element, beryllium, which he extracted as the oxide from emerald. Fredrich Wöhler first prepared metallic beryllium by reducing BeCl_2, with potassium metal. Thus the new element beryllium was discovered.

One caveat: until around 1948, beryllium (symbol = Be) was also known as Glucinium (symbol Gl), reportedly because of the sweetish taste of its chloride salts.

WARNING: Beryllium is considered to be highly toxic so do not, repeat do not taste or chew your precious emeralds!