Quartz pebbles

Quartz-Pebble Conglomerate Deposits. Known quartz-pebble conglomerate ores are restricted to a specific period of geologic time. These ore types occur in basal Lower Proterozoic beds unconformably situated above Archaean basement rocks composed of granitic and metamorphic strata. A number of commercial deposits are located in Canada and South Africa. Some subeconomic occurrences have been reported in Brazil and India... 

Quartz-pebble conglomerate Commercial deposits are available in Canada and South Africa, and... 

Quartz crystals, growth of, 14 93, 94 Quartz-pebble conglomerate uranium deposits, 17 520... 

Sedimentary Quartz-pebble conglomerates and associated formations Monazite, uraninite, brannerite Karnataka... 

Pyritic, uranium-bearing, quartz-pebble conglomerates have been found in Canada, in South Africa, in Brazil and in western Australia. The conglomerates are all of similar aspect and the minerals of interest are of similar character. 

Roscoe, S. M. Donaldson, J. A. 1988. Uraniferous pyritic quartz pebble conglomerate and layered ultramafic intrusions in a sequence of quartzite, carbonate, iron formation and basalt of probable Archean age at Lac Sakami, Quebec. Geological Survey of Canada, Paper, 88-1C, 117-121. 

Srinivasan, R. Ojakangas, R. W. 1986. Sedimen-tology of quartz-pebble conglomerates and quartzites of the Archean Bababudan Group, Dharwar Craton, South India evidence for early crustal stability. Journal of Geology, 94 199-214. 

Filter media Graded fire bricks pieces or quartz pebbles ... 

The Ellis Formation consists of a 30 m sequence of sandstone, siltstone, and intraformational conglomerates that overlie the Misthound Coal Measures. The contact between these formations is obscured by a sill of the Ferrar Dolerite that is also 30 m thick. At its type section beneath the western end of the Midnight Plateau the Ellis Formation consists of well-bedded yellow to white sandstone including thin layers of green sandstone, white siltstone, and quartz-pebble... 

Cyclical deposits of sandstone, shale and coal. Each cycle starts with a massive sandstone bed featuring large-scale trough cross-bedding and shale clasts at the base. Fossil leaves of Glossopteris and petrified tree trunks up to 60 cm in diameter are common, many are still upright. A quartz-pebble conglomerate occurs at the base of this formation Disconformity... 

The Queen Maud Formation is a coarse grained conglomeratic sandstone that lies unconformably on the rocks of the Weaver Formation. This unit is about 25 m thick and is equivalent to the basal quartz-pebble conglomerate of the Queen Maud Formation on Mt. Weaver. On Tillite Ridge in the Wisconsin Range the Queen Maud Formation is overlain by indurated till more than 30 m thick. This till is probably of Pleistocene or even of Pliocene age and thus is one of the many late Cenozoic glacial deposits in theTransantarctic Mountains that are collectively included in the Sirius Group. 

After the slotted grids have all been installed, they should be pushed toward the center of the converter and fitted together so that it is not possible for any of the 1/2" quartz pebbles to fall through. Then two or three strands of insulating rope may be used to caulk around the shell of the converter. No caulking should be used between e slotted grid sections as they must be placed to allow for some expansion. 

Catalyst should be handled gently and not thrown in recklessly or dumped from a great height. It is best handled in pails or in the original containers (after rescreening, if found necessary). After the specified amount of catalyst has been placed, the layer should be carefully levelled to insure uniform thickness in the catalyst bed. Failure to level properly will cause excessive flow through "thin spots" and may result in poor conversion. It has been found convenient to make three chalk marks around the columns and around the wall of the converter at a uniform distance above the grid. The bottom chalk mark represents the approximate top level of catalyst. The second chalk mark, two inches above the first, represents the anticipated level of the quartz pebbles over the catalyst. 

The third mark is placed two inches above the second mark and serves as a reference if the second mark is covered by quartz pebbles. 

Sulphur-burning plants with waste heat boilers frequently have superheater tubes in the converter. In smaller plants, the tubes of one of the boiler sections may also be inside the converter. There is usually but a few inches clearance between the baffle plate under the tubes and the catalyst. When installing catalyst in the layers containing these tubes, it is best to use the manholes on each side of the converter. This will facilitate the final levelling of the catalyst and the covering layer of quartz pebbles. 

Any thermocouple protecting wells inside the converter must be located in their proper places while the catalyst is being installed. They should be located exactly at the dividing line between the catalyst and the quartz pebbles in each instance as shown on the drawings. A handful of quartz may be placed under the end of the thermocouple well to prevent the tip of the thermocouple from being buried in the catalyst. 

Palaeo-placer U,Ti,Au,Zr,C,S Pyritic quartz-pebble conglomerate in fluvial channel deposits, uraninite-brannerite as matrix grains age, restriction 2900-2200 m.y. Elliot Lake, Canada Witwatersrand, R.S.A. 

Early Proterozoic time was characterized throughout the world by the initial deposition of layered supracrustal sequences composed predominantly of basal subaerial quartz-pebble conglomerate, shallow to deep water marine carbonate and clastic sedimentary rocks, iron formation and mafic volcanic or intrusive rocks. The depositional environments ranged from subaerial (fluvial) to marine, and the pre-depositional land surface was extensively peneplaned and chemically weathered,... 

The bulk of the world s uranium has been produced historically from (1) lower Proterozoic uraninite placer deposits in quartz-pebble conglomerates, (2) epigenetic uranium deposits in sandstones located in many cases at, or near, groundwater oxidation-reduction interfaces and (3) hydrothermal vein uranium deposits. These three distinctly different geologic environments provided most of the uranium that was produced from the 1940s to the early 1970s and they continue to be important exploration targets in the search for new uranium deposits. 

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