Tellurium (Te) is a semimetal/metalloid that can occur in its native state as a mineral. It has a metallic luster, a bright silvery color, a grayish streak, is rather soft (H = 2 to 2.5), and is heavy for its size. It is not malleable. Tellurium can break along several cleavage planes.
Tellurium is best known from precious metal telluride deposits, such as the Cripple Creek Mining District of Colorado, USA. In such deposits, Te is usually mixed with various metals and semimetals (e.g., Au, Ag, Pb, Ni, Fe, Bi, Sb). See calaverite & sylvanite.
Tellurium (= silver-colored mass at top-center) (field of view 2.7 cm across) in a quartz-pyrite hydrothermal vein (white = quartz; brassy gold = pyrite), hosted in altered porphyritic shoshonite lava (see rock matrix at right).
Deposit & Age: Emperor Gold-Silver Telluride Deposit, Mba Volcanics, Miocene.
Locality: Emperor Mine, near Vatukoula, Tavua Gold Field, northern Viti Levu, western Fiji Islands, southwest-central Pacific Basin (17º 30' 24" S, 177º 51' 12" E).