Images
Formula: CaMn2+Te4+4O10
Tellurite, manganese-bearing
mineral
Crystal System: Tetragonal
Specific gravity: 5.05 measured, 5.07 calculated
Hardness: 4
Streak: White
Colour: Pale green, colorless, pale grey, usually with thin brown coating
Luminescence: No fluorescence under long wave or short wave UV
Solubility: Dissolves easily in cold hydrochloric acid turning the solution yellow. Insoluble in both hot and
cold nitric acid, but slightly soluble in sulphuric acid with separation of a white milky material.
Common impurities: Ca
Environments
Localities
At the type locality, the Moctezuma Mine, Moctezuma, Moctezuma Municipality, Sonora, Mexico, denningite was
found associated with native tellurium,
tellurite, paratellurite
and several new tellurites or
tellurates. Among these new species is
spiroffite. Other minerals identified from the deposit, but not present
in the denningite specimens, are native selenium,
chalcomenite, emmonsite
and mackayite.
Two types of denningite have been found, green cleavable masses and colourless euhedral crystals.
Denningite usualy occurs as platy, cleavable masses, but a few euhedral crystals have been found. The masses
are a pale green with maximum dimensions 10 x 20 X 3 mm3, although their average size is
5 x 10 x 2 mm3. The crystals are thin plates with maximum dimensions of 1 X 1 X 0.1 mm3. On
broken surfaces, the crystals are colourless to pale grey; however, they are usually covered with a thin brown
coating.
Both types of denningite have a colourless streak and an adamantine lustre. They are translucent to transparent
(CM 7.3.443-452).
Denningite from Moctezuma - Image
Back to Minerals