Holmium, << HOHL mee uhm >> (chemical symbol, Ho) is one of the lanthanide metals. Its atomic number (number of protons in its nucleus) is 67. Its relative atomic mass is 164.93032. An element’s relative atomic mass equals its mass (amount of matter) divided by 1/12 of the mass of carbon 12, the most abundant form of carbon. For information on the position of holmium on the periodic table, see the article Periodic table .
The Swiss scientist J. L. Soret first identified holmium in 1878. In 1879, P. T. Cleve of Sweden independently discovered, and also named, the element. The name comes from Holmia, the Latin word for Stockholm, Sweden.
Holmium occurs in monazite and similar minerals that contain lanthanides. The metal has a silver color. It melts at 1474 °C and boils at 2700 °C. Its density is 8.78 grams per cubic centimeter at 25 °C.
