blende

It is said to require the reduction of about five thousand tons of the blende to produce one pound of radium.

It is what is called "zinc blende," and consists of zinc sulphide, or zinc and sulphur in combination.

The blende is first roasted in huge furnaces specially built for the purpose.

The Pierrefitte blende contains one part of gallium in four hundred thousand.

Zinc occurs in nature most commonly as sulphide (blende); it also occurs as carbonate (calamine) and silicate (smithsonite).