Tellurium
Te
atomic number
52
melting point
449.51°C

1. Place a small amount of finely powdered mineral into an open tube, then apply a hot flame to the bottom of the tube; telluride minerals will always leave a white to yellowish-gray sublimate in the tube.

2. Dissolve a small amount of powdered mineral in warm, concentrated sulfuric acid; tellurium-bearing compounds will give a beautiful, deep reddish-violet color to the solution; if distilled water is added to the cooled solution, the intense color will fade and a grayish-black precipitate will form on the bottom of the vessel.

3. Place a few small mineral fragments in a closed tube, then apply a hot flame to the bottom of the tube; tellurium-bearing compounds will yield tiny metallic beads of the metal and a white to colorless sublimate of TeO2.

4. Place several small mineral grains on a charcoal block, then apply the blowpipe flame; in the oxidizing portion of the flame, all tellurides yield a white coating of TeO2 which forms very close to the assay; in the reducing portion of the flame, the white sublimate volatilizes completely, coloring the blowpipe flame a pale green as it does so.