Cobalt blue, Cobalt Cerulean & Cobalt turquoise

Cobalt blue

Cobalt blue is very closely associated with smalt, its predecessor, since smalt is, in fact, finely to coarsely ground blue glass whose colour is due to small amounts of cobalt oxide added during its manufacture¹.

In this sense, although it was neither recognised nor named as cobalt at the time, its earliest documented use can be found on King Tutankhamun’s death mask, already associating this brilliant blue with kings and deities². In ancient Egypt, cobalt compounds were used to colour glass³.

Smalt as a tradeable pigment was probably first produced in Europe in the 16th century⁴.

The metal itself, which gave smalt its brilliant blue colour, was first isolated and identified as an element by the Swedish chemist and mineralogist Georg Brandt (1694-1768) around 1735, although it took several years for this identification to be accepted by the scientific community⁵. In 1742, Brandt was able to obtain the pure metallic form of the new metal, which he named Cobalt⁶.

According to Habashi⁷, the name cobalt has a clearly folklore background:

Once upon a time, towards the end of the 15th century, in the mines of the Erzgebirge (Ore Mountains), on the border between Saxony and Bohemia (Germany), a supposedly worthless mineral was found in large quantities. The miners disliked it, and with good reason: it contained arsenic and consequently had a profoundly harmful effect on their health.

The only reasonable explanation available to the miners at the time was the existence of Kobolds in the region — mischievous German goblins believed to inhabit mountains, caves and mines and to cause all sorts of trouble, such as throwing rocks, replacing one ore with another, driving miners insane, or even killing them⁸.

The word “cobalt” was later applied to ores that did not yield silver. When Brandt discovered the new material in an ore from the Skila copper works at Riddarhytta, which resembled copper ore in some of its properties but did not yield copper, the German miners of the time believed that this false ore had been bewitched — by whom else? The Kobolds, of course!

Thus, cobalt!

Although there are several theories concerning the etymology of the word “Kobold” and its relationship to the word “goblin”, it is particularly interesting that, in Greek mythology, Dionysus had followers who were dwarfs and mischievous, troublesome beings called Kobaloi (plural) [Kobalos (singular)], as mentioned by Aristophanes (445–386 B.C.)⁹ in his comedy Πλούτος (Plutos): “ὡς μόθων εἶ καὶ φύσει κόβαλος”¹⁰.

In fact, several scholars, including Shortland et al. (2026; see citation 2), have found the connection equally intriguing. Based on their analysis, they argue that Kobold/Kobald derives directly from the Greek Kobalos.

The pigment cobalt blue was developed by the French chemist Louis Jacques Thénard (1777-1857) in 1802, while searching for a blue pigment as beautiful as ultramarine¹¹.

By 1807, the pigment was being produced commercially to meet the needs of artists¹² — and it has continued to do so ever since.

cobalt cerulean

The first pigment based on cobalt and tin was prepared by the Swiss chemist Albrecht Höpfner in 1789¹³, although it received little significant recognition at the time¹⁴.

In 1805, the pigment — a compound of cobalt oxide and tin oxide — became available, and by 1870 (or possibly as early as 1860, under the name “coeruleum”¹⁵) it was being marketed commercially¹⁶.

Although today the name cerulean is applied to both PB35 and PB36 pigments, PB35 is the original cobalt-tin oxide pigment, whereas PB36, a cobalt-chromium-aluminium oxide pigment, was developed as a more affordable form of cerulean in the mid-19th century¹⁷.

According to the Oxford English Dictionary, “cerulean” is a borrowing from Latin combined with an English element. It derives from the Latin caeruleus and the suffix -an, representing the Latin -ānus, -āna, -ānum, meaning “of” or “belonging to”¹⁸.

Caeruleus is a difficult word to explain and translate. It is very closely associated with the sea rather than exclusively with the sky¹⁹.

As Osborn observes:

“The word is used of sea and sky (Vergil and Ovid passim.), of ice (Vergil G. I. 236), of snakes (Vergil G. IV. 452), of the nymph Cyane's hair (Ovid M. V. 732), of mountain tops (Ovid M. XI. 158), and of the eyes of German folk (Tac. Germania 7), where blue as a translation will not do, and 'sea-gleaming' is something of an evasion.”²⁰

She continues by observing that the common element in these uses is “iridescence”, the effect of vibrant light playing across a surface.

“We are immediately reminded of the Greek epithet κυάνεος (cyaneos), whose uses are closely parallel. Κυάνεος is a word used by Homer to describe the gleam of light upon a hard surface — the rainbow-like quality or iridescence seen, for example, on Achilles’ shield in Iliad book XVIII”²¹.

Caeruleus is considered the Latin equivalent associated with the meaning of κυάνεος. The term has also been connected etymologically with caelum (“sky”), describing a quality of light — a “beauteous heavenly light'”²².

cobalt turquoise

Cobalt titanate green spinel is a modern pigment whose colour is achieved through a solid-state reaction between cobalt and titanium oxides, producing a spinel-type structure that is resistant to fading, heat and chemical alteration.

It was developed in the mid-20th entury²³.

It received its name because of its colour, which resembles that of natural turquoise.