|Scandium, despite its rarity, is extremely widely diffused in nature. In almost all rocks from which the mountains of the earth, or rather the chief parts of the earth's crust are formed, scandium can be detected, as the comprehensive spectroscopic researches of Eberhard have shown. |
The more commonly occurring minerals which contain scandium are euxenite and keilhauite from certain localities, mica from Ytterby, and cassiterite and wolframite from the mountain ranges of Saxony and Bohemia, especially from Zinnwald in Saxony. They are all derived from granites or certain pegmatites.
It will be noticed that scandium occurs in certain rare earth minerals. However, it is by no means an invariable companion of the rare earth elements. In the course of some ten years of work on the rare earths, Urbain never met with scandium in any of his fractions, and Hicks failed to detect scandium in specimens of fergusonite, ceschynite, euxenite, and samarskite examined by him. Scandium occurs in gadolinite, but only in the deposits found at Ytterby. When scandium occurs in association with the rare earth elements, the yttrium group usually predominates, and hence the occurrence of scandium in Finnish orthite, a cerium mineral, is of interest.
The occurrence of scandium and the rare earth elements in the rare mineral wukite was discovered by Crookes, who isolated considerable quantities of scandia from this source. Wiikite is a black, amorphous mineral found with monazite in a felspar quarry at Impilaks, Lake Ladoga, Finland. Density, 4.85; hardness, 6. The mineral is feebly radioactive, and when heated to redness gives off water, hydrogen, sulphide, helium, a trace of neon, etc. The particular deposit of this mineral used by Crookes is now exhausted, and the other deposits do not appear to contain more than the merest traces of scandium.
The only known mineral in which scandium occurs as an essential constituent is the rare mineral thortveitite, (Sc,Y)2Si2O7. This is a greyish-green, translucent silicate of scandium and yttrium which has been found in pegmatite at Iveland, South Norway. Hardness, 6.5; density, 3.57. The mineral is orthorhombic (a:b:c = 0.7456:1:1.4912).
Scandium has been shown spectroscopically to occur in relative abundance in the sun and stars.
|Main article: Ekaboron |
Scandium corresponds very closely with ekaboron, one of the elements predicted by Mendeleeff when he put forward the periodic classification of the elements; and its discovery, coming only four years after the discovery of eka-aluminium or gallium, was a matter of great interest and assisted largely in the recognition of the merits of the periodic classification by chemists in general.