The Mineral
URANINITE
- Chemical Formula: UO2 , Uranium Oxide
- Class: Oxides and Hydroxides
- Uses: a major ore of uranium and radium, a source of helium and as a mineral specimen
Specimens
The structure is analogous to the structure of fluorite, CaF2. The structure of fluorite is highly symmetrical and forms isometric crystals such as cubes and octahedrons. Flourite also has four directions of perfect cleavage that produces octahedrons. However, in uraninite, crystals are rare and the cleavage is not usually observable.
A variety of uraninite is called pitchblende which is a combination of mostly uraninite and some other minerals. It is generally softer and less dense and usually botyroidal or earthy.
Remember, this is a highly radioactive mineral and should be stored away from other minerals that are affected by radioactivity and human exposure should definitely be limited.
PHYSICAL CHARACTERISTICS:
^- Color is black to steel black with tints of brown.
- Luster is submetallic to pitchy and dull.
- Transparency crystals are opaque.
- Crystal System is isometric; 4/m bar 3 2/m
- Crystal Habit is typically massive botryoidal, earthy, lamellar and reniform aggregates. Well-formed individual cubic and octahedral crystals are rare.
- Cleavage is poor in four directions (octahedral), and is rarely seen.
- Fracture is conchoidal.
- Hardness is 5 - 6
- Specific Gravity is near 10 when pure but often massive specimens are closer to 7 (heavy even for metallic minerals)
- Streak is brownish black.
- Associated Minerals include cassiterite, pyrite, native silver, autunite, uranophane, uranocircite, torbernite, meta-torbernite and other uranium minerals.
- Other Characteristics: highly radioactive!
- Notable Occurences include Bergen, Germany; Autun, France; Cornwall, England; Mitchell Co., North Carolina and Mt. Spokane, Washington, USA; Zaire; wilberforce and Great Bear Lake, Canada; Portugal and France.
- Best Field Indicators are luster, color, radioactivity and streak.
 Amethyst Galleries' Mineral Gallery MINERALS |
URANINITE specimen ura-1
$ 42.00
$ 42.00
Dims: 4.5" x 1.7" x 1.4" (11.4 x 4.3 x 3.6 cm)
Wt: 11.3 oz. (321.0 g)
Huskin #7 Mine, Coconino County, Arizona, U.S.A.
This odd hand specimen consists of part of a fossilized tree branch or thin trunk that has been replaced with, among other things, black massive Uraninite. This material has a flat black color and a matte luster, and shows no evidence of crystal form. Though it does show some of the wood's original form, I think that much of this form has been destroyed in the fossilization process. Accompanying the Uraninite is a substantial amount of material whose color ranges from white to yellow to a pale orange-brown. According to documentation, the yellow and orange-brown materials are made up of Coconinoite, named after the county in which this piece was found. There is not really any host rock present, and the Uraninite itself appears to make up a matrix for the other minerals.
ura-1 ($ 42.00)
Huskin #7 Mine, Coconino County, Arizona, U.S.A.
URANINITE specimen ura-2
$ 36.00
$ 36.00
Dims: 4.4 x 3.1 x 1.4" (11.2 x 7.9 x 3.6 cm)
Wt: 10.3 oz. (291.3 g)
Huskin #7 Mine, Coconino County, Arizona, U.S.A.
This hand specimen consists of part of a fossilized tree trunk or branch that has been replaced with Uraninite. Due to the replacement process, there is not any crystalline form. The Uraninite has the basic black color and a matte luster. There are streaks of color on the outer surface of the specimen- many of these are indicative of the presence of coconinoite, a complex phosphate of iron, aluminum, and uranium. If there are any crystals of this material present, they are microscopic in size.
ura-2 ($ 36.00)
Huskin #7 Mine, Coconino County, Arizona, U.S.A.
URANINITE specimen ura-3
$ 25.00
$ 25.00
Dims: 2.1 x 1.4 x 1.1" (5.3 x 3.6 x 2.8 cm)
Wt: 1.24 oz. (35.1 g)
Huskin #7 Mine, Coconino County, Arizona, U.S.A.
This thumbnail specimen consists of a chunk of massive Uraninite, and is of the variety known as "Pitchblende". It has no discernable crystal form and is black in color and dull in luster. A few dark brown veins run through the material, but I do not know what constitutes them. Though the Uraninite does not have any crystal form, the specimen as a whole does have the form of a piece of wood- this is due to the fact that it is, in effect, a piece of petrified wood, wherein the wood was replaced by the Uraninite. There is no host rock present.
ura-3 ($ 25.00)
Huskin #7 Mine, Coconino County, Arizona, U.S.A.
URANINITE specimen ura-4
$ 30.00
$ 30.00
Dims: 2.2 x 1.5 x 1.1" (5.6 x 3.8 x 2.8 cm)
Wt: 2.45 oz. (69.6 g)
Huskin #7 Mine, Coconino County, Arizona, U.S.A.
This specimen consists of a piece of petrified wood that was replaced by Uraninite rather than agate, jasper, or coal, as is usually the case. The Uraninite is massive, possessing no crystal form or tendencies, and has a black color and a matte luster. There are substantial amounts of material whose color ranges from brown to white- they might be made up of different uranium-bearing minerals, especially the yellow material. The piece shows a definite wood-like grain in many areas. As with our other specimens from this locality, there is no host rock present.
ura-4 ($ 30.00)
Huskin #7 Mine, Coconino County, Arizona, U.S.A.
URANINITE specimen ura-5
$ 60.00
$ 60.00
Dims: 1.2 x 0.8 x 0.5" (2.9 x 2.0 x 1.3 cm)
Wt: 8 g
Schwartzwaelder Mine, Jefferson County, Colorado, U.S.A.
A small amount of massive Uraninite is embedded in the metallic base of this thumbnail specimen. The Uraninite is difficult to determine- at first, I thought that it was the gray-black, semimetallic material that appears to make up most of the mass of the specimen. Howver, my Geiger-Muller counter registers very little radioactivity in the piece- too little for this material to be Uraninite. There appears to be a very small amount of a dull, black material at the thinner end of the piece- I think that this is actually the Uraninite. Given the relatively high density of the specimen and the apparent presence of pyrite,I think that the semimetallic material is either a metallic oxide or sulfide.
ura-5 ($ 60.00)
Schwartzwaelder Mine, Jefferson County, Colorado, U.S.A.