1Up Science - aluminium Information

The extraction of aluminium is a two-stage process. In the first stage bauxite is crushed to extract aluminium oxide (alumina). In the second stage pure aluminium is extracted from the alumina by electrolysis.

http://www.1upscience.com/aluminium

Yttrium - Periodic Table - All Metals & Forge

www.steelforge.com

All Metals & Forge provides a periodic table of elements, this page discusses the element Yttrium. We give a brief history of Yttrium; and list the atomic number, atomic symbol, atomic weight, and electron configuration of Yttrium.

http://www.steelforge.com/elements/yttrium.htm

praseodymium

Praseodymium - (Gr. prasios, green, and didymos, twin), Pr; at. wt. 140.90765(3); at. no. 59; m.p. 931 deg C; b.p. 3520 deg C; sp. gr. 6.773; valence 3.

http://www.speclab.com/elements/praseodymium.htm

Principal Metals-Praseodymium

(Gr. prasios, green, and didymos, twin) In 1841 Mosander extracted the rare earth didymia from lanthana; in 1879, Lecoq de Boisbaudran isolated a new earth, samaria, from didymia obtained from the mineral samarskite.

http://www.principalmetals.com/utilities/59.htm