Holmium hardness

Dysprosium - the atomic number is 66 and the chemical symbol is Dy. The name derives from the Greek dysprositos for hard to get at , due to the difficulty in separating this rare earth element from a holmium mineral in which it was found. Discovery was first claimed by the Swiss chemist Marc Delafontaine in the mineral samarskite in 1878 and he called it philippia. Philippia was subsequently found to be a mixture of terbium and erbium. Dysprosium was later discovered in a holmium sample by the French chemist Paul-Emile Lecoq de Boisbaudron in 1886, who was then credited with the discovery. It was first isolated by the French chemist George Urbain in 1906. 

Fig. 7.10. Schematic H-T phase diagrams for single-crystal holmium in fields applied parallel to the (easy) h-axis (left) and to the (hard) a-axis (right) [after Koehler et al. (1%7)].

Discovery Paul-Emile Lecoq de Boisbaudran in France in 1886 found a new element in the REM holmium, earlier discovered by Cleve. The discovery was hard work (dysprositos in Creek), so the new element was given the name dysprosium. 

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