Mineral Species containing Tellurium (Te)

Diagnostic tests: 
Tellurium and tellurides are detected by heating the powdered mineral in a test tube with 5cc of concentrated H₂SO₄ acid. The presence of a reddish-violet color suggests Te. After cooling, addition of water will cause the color to disappear and a grayish black precipitate of tellurium will appear.

Open tube test of the powdered mineral oxidizes tellurium to TeO₂ which passes up the tube as a white smoke and condenses near the heated part as a white coating. The coating can be fused into a globule which is yellow when hot and white when cold.

Closed tube test of the powdered mineral causes tellurium to volatize and condense on the hot glass as fused globules having a metallic luster. Minor amounts of white oxide may be produced along with the metallic globules.

On charcoal, the blowpipe produces a white sublimate near the assay somewhat resembling the test for antimony. The sublimate can be blasted with the blowpipe flame and imparts a pale greenish color to the flame test.