URANIUM ROLL FRONTS

	Sandstone uranium deposits are formed in aquifers through which uranium bearing groundwater flows. The uranium and other metals dissolved in the ground water such as molybdenum, vanadium, selenium, and arsenic precipitate out of the ground water when the ground water flow crosses an oxidation/reduction interface in the sandstone. This forms a uranium deposit known as a roll front. Roll fronts are found around the world and are the type of uranium deposit deposit mined by the in-situ mining method. The drawing above shows a schematic of a uranium roll front. This drawing is provided courtesy of John Hamrick of UMETCO Minerals Corporation. Click on the image to view a larger version of it!
The structure shown in the drawing above can be seen in the photograph below of a uranium roll front in the wall of an open pit mine in Wyoming. This photograph has been "flipped" left to right so that the visible structure in the image is aligned identically to the roll front shown in the previous drawing. This photograph is courtesy of Power Resources, Inc. (PRI). The prominent black banding in the photograph is uranium mineralization. The black banding in the photograph to the right corresponds to the yellow area immediately to the left of the green roll front "nose" in the drawing above. The area in the upper left of the photograph corresponds to the hematitic core of the roll front described in the drawing above. The photograph to the right also corresponds in orientation to the uranium roll front drawing below.
	The drawing to the left shows a roll front being in-situ mined via wells completed in the front. This drawing is courtesy of Cogema Mining Incorporated (COMIN). The in-situ mining method shown in the drawing below reverses the depositional process for the uranium mineralization. Click on the image for a larger version of it! The shale or mudstone components shown in the drawing to the left are not present in the photograph above. The red area in the drawing corresponds to the black area in the photograph. The hematitic core of the roll front described in the first drawing (shown in orange/tan) corresponds to the yellow area in the drawing to the left.