Tellurium (Native)

Discovered in 1783; IMA status: Valid (pre-IMA; Grandfathered)

Chemistry

Chemical Formula:

Te

Elemental Tellurium

Atomic Number:

52 

Molecular Weight:

127.60 gm

Composition:

Tellurium

100.00 %

Te

100.00 %

Classification

Mineral Classification:

Elements

Strunz 8th Ed. ID:

1/B.03-40

Nickel-Strunz 10th Ed. ID:

1.CC.10

1 : ELEMENTS (Metals and intermetallic alloys; metalloids and nonmetals; carbides, silicides, nitrides, phosphides)
C : Metalloids and Nonmetals
C : Sulfur-selenium-iodine

Related to:

Selenium Group.

Members of Group:

Selenium Group: Selenium, Tellurium

Varieties:

Selen-tellurium

Synonyms:

Lionite (of Berdell), Native Tellurium, Sylvanite (of Kirwan)

Crystal Data

Crystallography:

Trigonal - Trapezohedral

Crystal Habit:

Crystals, to 3.5 cm, prismatic and acicular || [0001] with (+) and (–) rhombohedra equally developed; also massive, columnar to fine granular. 

Twinning:

None

Physical Properties

Cleavage:

Perfect on {1010}, imperfect on {0001}

Fracture:

n/a

Tenacity:

Brittle

Moh's Hardness:

2.0 - 2.5; Vickers: VHN₁₀₀=48-66 kg/mm²

Density:

10.58 (g/cm³)

Luminescence:

None

Radioactivity:

Not Radioactive

Optical Properties

Color:

Tin-white; in polished section, white

Transparency:

Opaque

Luster:

Metallic

Refractive Index:

R1–R2: (400) 58.1–64.2, (420) 58.4–64.8, (440) 58.7–65.3, (460) 59.1–65.7, (480) 59.3–66.1, (500) 59.7–66.5, (520) 60.0–66.8, (540) 60.1–67.0, (560) 60.2–66.8, (580) 60.0–66.6, (600) 59.5–66.0, (620) 58.8–65.2, (640) 57.9–64.3, (660) 57.1–63.4, (680) 56.1–62.3, (700) 55.0–61.3

Birefringence:

0.000 (opaque)

Dispersion:

None

Pleochroism:

Feeble

Anisotropism:

Fairly strong; color in reflected light: white

Occurances

Geological Setting:

In hydrothermal veins; may be of both primary and secondary origin; a sublimate in volcanic fumaroles.

Common Associations:

Gold, Sylvanite, Empressite, Altaite, Pyrite, Galena, Alabandite, Barite, Quartz, Carbonates.

Common Impurities:

Se, Fe, Bi, S

Type Locality:

Mariahilf Mine, Faţa Băii (Facebánya; Facebay; Fatiabaja), Zlatna (Zalatna; Zalathna), Alba County, Romania

Year Discovered:

1783

View mineral photos:

Tellurium Mineral Photos and Locations

Unusual Gem Categories

Metallic Gems, Native Elements

More Information

Mindat.org
Webmineral.com

Tellurium is a chemical element similar to Copper, Silver and Gold. Crystalline Tellurium has a silvery-white appearance with a metallic lustre when pure. It resists oxidation by air and is nonvolatile. Tellurium is mildly toxic and people exposed to even very small amounts of it in air, develop "tellurium breath", which has a garlic-like odor. Tellurium is one of the rarest stable solid elements in the Earth's crust with an abundance comparable to that of Platinum. The picture above is a gem of Quartz matrix with bright, metallic native Tellurium crystals from the Bambolla Mine, Moctezuma, Mun. de Moctezuma, Sonora, Mexico. Native Tellurium is often associated with white to yellow Tellurite and grayish-white to creamy yellow Paratellurite which are both Tellurium Oxide minerals.

Tellurium was discovered in 1783 by Australian mineralogist Baron Franz Joseph Müller von Reichenstein (1740 or 1742-1825 or 1826) in Gold ore samples from the Mariahilf Mine, Fata Băii, Zlatna, Transylvania, Romania. Müller isolated an unknown metal from the samples but after three years and more than fifty tests he could not identify it. Apparently in frustration, he gave it the names aurum paradoxium and metallum problematicum. Müller sent a sample to German chemist Martin Heinrich Klaproth (1743-1817) who was able to identify the unknown metal as a new element in 1798. He named it tellurium from the Latin name of planet Earth, tellus, and credited Müller with its discovery.

Tellurium distribution: in Romania, from Faţa Bâii (Zlatna, Faczebaj) [TL] and Baia-de-Aries (Offenbánya). At the Fossa volcano, Vulcano, Lipari Islands, Italy. From the Tolbachik fissure volcano, Kamchatka Peninsula, Russia. Large cleavages at the Kochbulak gold deposit, Chatkal-Kuramin Mountains, eastern Uzbekistan. In the USA, from many localities in Colorado, including Cripple Creek, Teller County; in the Magnolia, Gold Hill, Ballarat, and Central districts, Boulder County; and at the Vulcan mine, Gunnison County; in Nevada, at the Mohawk and Clermont mines, Goldfield district, Humboldt County, and from Delamar, Lincoln County At the Moctezuma (Bambolla) mine, 12 km south of Moctezuma, Sonora, Mexico. From the El Indio mine, east of La Serena, Coquimbo, Chile. At Kalgoorlie, Western Australia. In the Teine mine, northwest of Sapporo, Hokkaido, and in the Kawazu mine, near Sizewka, Shizuoka Prefecture, Japan. From the Emperor mine, Vatukoula, Viti Levu, Fiji Islands. At the Guilaizhuang gold deposit, Shandong Province, and in the Dashuigou tellurium deposit, Sichuan Province, China. Additional minor localities are known.
 

  
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