40 Zirconium

The semiprecious gemstone Zircon comes in a variety of colors from blue, yellow, green, brown, orange, red and occasionally purple. It is transparent and can have cat's eye in rare instances. The various forms of zircon have been known as gemstones since ancient times. During the middle ages zircon was thought to induce sleep, promote riches, honor and wisdom; drive away plagues and evil spirits. The Hindus described the Kalpa Tree a symbolic offering to early gods, as being made of glowing precious stones with zircon leaves.
The word Zircon comes from Persian zargûn (literally "gold colour"); in Arabic the "k" was substituted for "g": zarkûn > zircon. It describes one of the colours of the gemstone (Zr(SiO)₄). Also other precious stones such as jacinth (or hyacinth), and jargon containing Zirconium are widely distributed and known by ancients.

Zircon was not known to contain a new element until Martin Heinrich Klaproth (1743-1817), in 1789, analyzed a jargon from Ceylon and found a new earth, jargonia or zirconia ("Zirkonerde", ZrO₂) (note), which Abraham Gottlob Werner (1749-1817), geologist at Freiberg Mining Academy, named zircon (silex circonius).

Was ist dieses nun für eine Erde? Kann ich solche für eine bisher ungekannte, selbständige, einfache Erde halten? In so fern mir nicht bewußt ist, ob sich eine oder andere der bisher bekannten fünf einfachen Erden künstlich so umändern lasse, daß sie die nemlichen Erscheinungen und Verhältnisse, wie diese Erde aus dem Zirkon, gewährte, glaube ich mich dazu wohl berechtigt, und lege selbiger, bis dahin, daß man sie vielleicht in mehrern Steinarten antreffen, und anderweitige Eigenschaften, welche eine angemessenere Benennung veranlassen mögten, an ihr kennen lernen wird, den Namen Zirkonerde (Terra circonia) bey.

Translation (more or less):
What is this for an earth? May I assume it for an up to now unknown, independent, simple earth? Insomuch I am not aware of, that one or another of the up to now known five simple earths can be artificially altered, so that it shows the appearance and relations as this earth from the zircon, I consider myself entitled to, until it is perhaps found in other kinds of stones, with further properties, giving cause to a more appropriate name, to give it the name zirkon earth (zirkonia).

Later, Klaproth found his "Zirkonerde" also in a jacinth (or hyacinth) from Ceylon, and considered the name "Hyacintherde" more appropriate (note). This name is found in some of the later literature.

In 1808, Sir Humphry Davy (1778-1829) did experiments for the decomposition of alumine, silex, zircone, and glucine. He failed to isolate the metals in these, as he reported in his paper for the Royal Society of London on 30 June 1808, but he suggested names for the metals (note):