From the CRC handbook of Chemistry and Physics, CRC Press, Cleveland, 55th ed., 1974-75 "The Elements" by C.R. Hammond. page B-6
SCANDIUM (L. Scandia, Scandinavia), Sc; at. wt. 44.9559; at. no 21; m.p. 1541 C; b.p. 2831 C; sp.gr. 2.989 (25 C); valence 3. On the basis of the Periodic System, Mendeleev predicted the existence of ekaboron, which would have an atomic weight between 40 of calcium and 58 of titanium. The element was discovered by Nilson in 1876 in theminerals euxenite and gadolinite, which had not yet been found anywhere except in Scandinavia. By processing 10 kg of euxenite and other residues of rare-earth minerals, Nilson was able to prepare about 2 gms of scandium oxide of high purity. Cleve later pointed out that Nilson's scandium was identical with Mendeleev's ekaboron. Scandium is apparently a much more abundant element in the sun and certain stars than here on earth. It is about the 23rd most abundant element in the sun compared to the 50th most abundant on earth. It is widely distributed on earth, occuring in very minute quantities in over 800 mineral species. The blue color of beryl (aqua-marine variety) is said to be due to scandium. It occurs as a principal component in the rare mineral thortveitite, found in Scandinavia and Malagasy. It is also found in the residues remaining after the extraction of tungsten from Zinnwald wolframite, and in wiikite and bazzite. Most scandium is presently being recovered from thortveitite or as a by-product of the extraction of unranium from davidite, which contains about 0.02% Sc2O3. Metallic scandium was first prepared in 1937 by Fischer, Brunger, and Grieneisen, who electrolyzed a eutectic melt of potassium, lithium, and scandium chlorides at 700-800 C. Tungsten wire and a pool of molten zinc served as the electrodes in a graphite crucible. Methods of producing themetal are now somewhat more complicated. The production of the first pound of 99% pure scandium metal was announced in 1960 as having been made under a U.S. Air Force contract. Scandium is a silvery-white metal which develops a slightly yellowish or pinkish cast upon exposure to air. It is relatively soft, and is reported to resemble yttrium and the rare-earth metals more than it resembles aluminum or titanium. It is a very light metal and has a higher melting point than aluminum, making it of interest to designers of space missiles. Scandium is not attacked by a 1:1 mixture of conc. HNO3 and 48% HF. This mixture can be used to dissolve tantalum from scandium. Scandium reacts rapidly with many acids. Eleven isotopes of scandium are recognized. The metal is still expensive, costing about $20 to $60 or more per gram, or about $7500 per pound with a purity of about 99.9%. It has been reported that several hundred pounds of scandium have now been produced (1970). Scandium oxide costs about $8/gm. Little is yet known about the toxicity of scandium; therefore it should be handled with care.
