Chemical dating of uraninite

chemical dating of uraninite

Are natural uraninites chemically heterogeneous?

Uraninite satisfies the first criterion but many workers ( Janeczek and Ewing, 1995, Kempe, 2003, Alexandre and Kyser, 2005, Deditius et al., 2007) have demonstrated that most natural uraninites are chemically heterogeneous at micron scale level, resulting analytical complications, if used for dating.

What is uraninite made of?

In granites such as the Urgeiriça deposit, Portugal ( Basham et al., 1982 ), uraninite frequently occurs as disseminated crystals ( Fig. 11 A) surrounded by an assemblage consisting of pyrite and carbonaceous material with apatite ( Fig. 11 B).

What is the solubility of uraninite under reducing conditions?

Under reducing conditions, the solubility of uraninite is extremely low; however, this is moderated to some extent by the presence of minor U 6+ and radiogenic Pb 2+ in the structure, the latter increasing substantially with time.

What is the molecular formula of uraninite?

Uraninite PubChem CID 197737 Structure Find Similar Structures Molecular Formula H4O2U Synonyms Uraninite dioxouranium (1+) 1317-99-3 Pi ... Molecular Weight 274.06 g/mol 2 more rows ...

Are the uraninites found at the grain boundary included in host minerals?

Although the studied uraninites occur at the grain boundary, they are included in the host minerals and their compositions are otherwise indistinguishable from the ∼1.20 Ga uraninites excepting the PbO contents.

What is uraninite made of?

In granites such as the Urgeiriça deposit, Portugal ( Basham et al., 1982 ), uraninite frequently occurs as disseminated crystals ( Fig. 11 A) surrounded by an assemblage consisting of pyrite and carbonaceous material with apatite ( Fig. 11 B).

What is hydrothermal uraninite?

Hydrothermal uraninite typically occurs as veins, sometimes in massive or colloform and botryoidal (pitchblende) form. Ore-forming processes are controlled by timing, source, fluids, and the trap for uranium.

Do basement uraninites contain rare earth elements?

Although none of the pristine, unaltered uraninites that formed during the above mentioned events contain significant intrinsic minor or rare earth elements, the basement uraninites are consistently much enriched in thorium compared to those from the supracrustal.

What is the chemical formula for uranium?

General Uraninite Information. Chemical Formula: UO2. Composition: Molecular Weight = 270.03 gm. #N#Uranium 88.15 % U 100.00 % UO 2. #N#Oxygen 11.85 % O. #N#______ ______. #N#100.00 % 100.00 % = TOTAL OXIDE.

What is the composition of uraninite?

Composition of Uraninite. Gummite is a yellow oxidation product of uraninite. It consists of uranium oxides, silicates and hydrates. Its yellow color is often an indication that uranium minerals are nearby. This specimen consists of a mixture of gummite (yellow), uraninite (black), and zircon (brown).

What is the origin of the name uraninite?

Uraninite used to be known as pitchblende (from pitch, because of its black color, and blende, a term used by German miners to denote minerals whose density suggested metal content, but whose exploitation, at the time they were named, was either unknown or not economically feasible [from blenden meaning to deceive/).

What is the solubility of uraninite under reducing conditions?

Under reducing conditions, the solubility of uraninite is extremely low; however, this is moderated to some extent by the presence of minor U 6+ and radiogenic Pb 2+ in the structure, the latter increasing substantially with time.

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