THE MINERAL ANDERSONITE
- Chemistry: Na2CaUO2(CO3)3-6H2O, Hydrated Sodium Calcium Uranyl Carbonate
- Class: Carbonates
- Uses: very minor ore of uranium and as mineral specimens.
Andersonite is a rare uranyl carbonate mineral, that was only described in the last half century. It has a luster that seems to glow and in fact it is very fluorescent. Andersonite specimens will usually glow a bright lemon yellow in ultraviolet light. The mineral is formed as a secondary mineral and as an efflorescent crust in uranium mines. Efflorescent means it forms on the surface of a rock by the evaporation of water when in contact with the dry air of the mine. Thus, some andersonite specimens are the result of human intervention (albeit unintentional) and some minerologists do not consider these to be pure mineral specimens.
Andersonite’s lovely color and unique glow, as well as it’s rarity and fluorescence, make it a wonderful mineral for rare mineral collectors. Remember, this is a radioactive mineral and should be stored away from other minerals that are affected by radioactivity and human exposure should definitely be limited.
- Color is yellow to a yellowish green.
- Luster is vitreous to pearly.
- Transparency crystals are commonly translucent.
- Crystal System is trigonal.
- Crystal Habits include small rhombohedral crystals that have angles close to 90 degrees, making them pseudocubic. Also found commonly as crusts.
- Cleavage is perfect in three directions forming rhombs.
- Fracture is conchoidal.
- Hardness is 2.5
- Specific Gravity is 2.9 (average).
- Streak is pale yellow.
- Associated Minerals are gypsum and other uranium carbonates such as bayleyite, Mg2(UO2)(CO3)3-18H2O and liebigite, Ca2(UO2)(CO3)4-11H2O.
- Other Characteristics: radioactive, and fluoresces bright lemon-yellow under ultraviolet light.
- Notable Occurrences include the Hillside Mine, Bagdad, Arizona and the Jim Thorpe Mine, Pennsylvania, USA.
- Best Field Indicators are its crystal habit, radioactivity, fluorescence and associations.