Carlfriesite

carlfriesite

dickite

hessite

bornite

Images

Formula: CaTe4+2Te6+O8
Tellurite
Crystal System: Monoclinic
Specific gravity: 6.3 measured, 5.7 calculated
Hardness: 3½
Streak: Very pale yellow
Colour: Yellow
Luminescence: No fluorescence under long wave or short wave UV
Environments

Hydrothermal environments

Localities

At the type locality, the Bambollita Mine, Moctezuma, Moctezuma Municipality, Sonora, Mexico, the altered wallrock consists of granular quartz, some interstitial sericite, and scattered white dickite pseudomorphs after sanidine. The ore veins carry calcite and baryte as gangue with scattered grains of bornite, hessite and galena.
Oxidation has produced fairly abundant bright yellow carlfriesite and colourful green crusts, which are a mixture of an amorphous copper - tellurium compound and dickite. Less common are electrum, cerussite, chlorargyite, and an orthorhombic copper tellurite. Carlfriesite occurs as botryoidal crusts lining cavities and less frequently as tiny sprays of sharply euhedral crystals. It also commonly fills cleavage-plane fractures in the baryte or occurs in tiny veinlets cutting the rock in the vicinity of sulphide grains; rarely it is implanted directly on hessite or bornite (MM 40.127–130).
Carlfriesite from the Bambollita Mine - Image

At the Moctezuma Mine, Moctezuma, Moctezuma Municipality, Sonora, Mexico, carlfriesite occurs as botryoidal crusts and well formed, bright yellow monoclinic crystals to 5 mm, associated with tellurite and moctezumite. Other associated minerals include cerussite, chlorargyrite, hessite, galena, bornite and secondary tellurium minerals (Minrec 55.6.839).
Carlfriesite from the Moctezuma Mine - Image

On the Upper dumps, North Star Mine, Mammoth, Tintic Mining District, Juab County, Utah, USA, carlfriesite is extremely rare; however, nice, transparent, pale yellow euhedral crystals up to 1 mm have been found. Associated minerals include goldfieldite, pyrite, svanbergite, utahite, xocolatlite, xocomecatlite and zemannite, on a matrix of quartz and baryte (AM 55.2.187)>
Carlfriesite from the North Star Mine - Image

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