Antimony
Sb
atomic number
51
melting point
630.63°C

1. Using the oxidizing portion of the flame, heat up a few mineral fragments on a charcoal block; a white sublimate of Sb2O3 is produced accompanied by dense white, odorless (if no sulfur or arsenic is present) fumes; the sublimate forms very close to the assay and is quite volatile

2. When heated in an open tube, most antimony sulfides yield a straw yellow sublimate of SbSO4 which turns white upon cooling; when heated in a closed tube, a black sublimate of SbS2O is produced which turns a rich reddish-brown upon cooling

3. When exposed to the reducing portion of the flame, antimony imparts a pale greenish color to the flame; (care must be taken not to use platinum forceps or tweezers in this test)

4. Add a small amount of powdered mineral sample to a beaker containing nitric acid, then heat the mixture using a lamp, candle, or Bunsen gas burner; a white insoluble precipitate of HSbO3 is produced