Tellurium

In nature, tellurium is found in the Earth's crust, 0.002 ppm, both native, associated with silver and gold, and in minerals such as tetradymite, altaite, coloradolite and tellurite [5]. The isotopes found in nature are ¹²⁰Te (0.089 %, stable), ¹²²Te (2.46 %, stable), ¹²³Te (0.87%, stable), ¹²⁴Te (4.61 %, stable), ¹²⁵Te (6.99 %, stable), ¹²⁶Te (18.71 %, stable), ¹²⁸Te (31.79 %, stable) and ¹³⁰Te (34.48 %, stable) [5].

In pure solid form, tellurium exist in a hexagonal rhombohedral crystal structure or as an amorphous structure [5].