Guilleminite

Specimen Notes Crystals - The Guilleminite occurs as intergrown masses of crystals that present a prismatic appearance, deposits of microcrystals and encrustations. All of these forms are often in close proximity to each other. The few crystal clusters that do occur are so intimately grown into the surrounding Guilleminite and host rock that all that can be stated is that they are prismatic in form. The intermediate sized deposits, such as seen in 001b, appear to be massive crystalline deposits. The crystal clusters that are easily examined appear as radial clusters. These clusters can occur in parallel, giving a platy appearence, as seen in image 001d. Occurance - The Guilleminite deposits appear to have been deposited after the time that the host rock was formed. While Calcite is present on the specimen, the Guilleminite occurs primarily on the silicate host rock, but can also occur in proximity to the Calcite. Image 001g shows the host rock, as well as several plaques of Calcite or Aragonite, around a small deposit of Guilleminite. The dark mineral appears to be the selenian variety of Digenite (Cu9S5). Other Uranium Minerals - Rutherfordine appears within the main mass of Guilleminite as slightly darker crystalline masses. It is somewhat difficult to discern this mineral from the Guilleminite as they both have similar color. Only Rutherfordine's platy crystalline form, slightly more reflective luster, and a slightly darker color differentiate it optically. It is most easily seen in the center of the lower left quadrant of image 001e. A deposit of Sklodowskite crystals, approximately 0.1 mm in length, is seen in image (001h). It occurs adjascent to the main deposit of Guilleminite, in an area where the Guilleminite occurs as a crusty, dusting, deposit. The Sklodowskite crystals are too small to be accurately observed at 30X magnification. Luster - The Guilleminite, on this specimen, has a dull, earthy luster. The crystals have a slightly smoother appearance than the crusts, but are also of a dull luster.   Specimen Characteristics Dimensions: 2.67 cm × 2.28 cm × 1.52 cm Weight: 16.9 g Radioactivity:     Specimen & Background (30 minute average):     Background (30 minute average):         (2.5 cm from detector)   31 counts/hour (g-rays) 18 counts/hour (g-rays)   :

Specimen #2

Specimen Notes Occurrence - The specimen has no host rock pressent. A substrate that appears to have formed on the host rock consists of a mixture of lime bonding together randomly oriented Sklodowskite crystals. On this is a layer of sklodowskite crystals growing in parallel, with botryoidal Heterogenite nodules included in this layer. The outermost layer consists of dark green acicular Malachite (?) crystals, on which granularly shaped radial clusters of Guilleminite has grown. At the perifery are both Sklodowskite and Cuprosklodowskite crystals, plus a dagger shaped light green crystal of an as yet unidentified mineral. Crystals - The Guilleminite crystals can be seen to be acicular, but are too small to see more than that at 30X magification. Sklodowskite - The mass of Sklodowskite can only be seen as a packed mass of columns, and little beyond that can be seen. The freely grown crystals at the periphery of the Malachite (?) can clearly be seen, with many well terminated crystals. Cuprosklodowskite - The few Cuprosklodowskite crystals that occur are often seen growing freely, and in close proximity to, the Sklodowskite crystals. Their flat bladed shape with chisel-point termination clearly distinguishes them from the Sklodowskite. Malachite (?) - The dark green Malachite crystals are clearly acicular, and not packed into botruoidal masses. It is this lack of packing that makes their identification somewhat uncertain. (unknown) - The dagger shaped crystals of this mineral are found growing along the periphery of the Malachite (?) crystals, and occasionally among them. Appearence -   Diaphaniety - The crystal masses of Guilleminite are opaque, and it is believed that the individual crystals are as well. Luster - The individual crystals of Guilleminite are too small to determine their luster. The crystal clusters do show some dim highlights under the microscope. However, this may be from other material embedded within these clusters.     -     Specimen Physical Properties Size 6.48 cm 3.6 cm 4.32 cm Weight: 53.15 grams 22° C. 40% R/H g-Radiation Level:   cmp   msieverts background: 20 cpm