Search results for "Gypsum"
showing 4 items of 84 documents
Guano-related phosphate-rich minerals in European caves
2019
International audience; Guano is a typical deposit found in caves derived from the excretions of bats and in minor cases of birds. These organic deposits decompose and form a series of acid fluids and gases that can interact with the minerals, sediments, and rocks present in the cave. Over sixty phosphates are known and described from caves, but guano decay also often leads to the formation of nitrates and sulfates. In this study twenty-two European caves were investigated for their guano-related secondary minerals. Using various analytical techniques, seventeen phosphates, along with one sulfate (gypsum), were recognized as secondary products of guano decay. Among those minerals, some are …
The dissolution of gypsum of Disueri reservoir left bank
2011
Results of a laboratory research programme on the rate of dissolution of selenitic gypsum are reported and discussed. The tested gypsum samples have been recovered from boreholes drilled in a thick layer outcropping on the left bank of Disueri reservoir located near Gela in Sicily. The tests carried out demonstrate that the rate of dissolution Rd depends essentially upon the velocity v of water flowing over the surface of the gypsum. Values of Rd range from 0.94 to 3 kg/(m2 • day) for v values from 0.05 to 0.20 m/s. Such high rates can account both for the rapid evolution of the existing cavities and for the creation of new caves within the gypsum mass subsequent to the impounding of the re…
Mise en évidence d'un Sénonien gypseux sous la série phosphatée du bassin des Ouled Abdoun: un nouveau point de départ pour l'origine des zones déran…
2013
In the Ouled Abdoun sedimentary basin (Morocco), the phosphatic series is composed of regular interbedded phosphatic and marly limestone layers. Exploitation of the phosphate in some deposits in this basin collides frequently with problems bound to the existence, in the phosphatic series, of disturbed areas (sterile bodies) qualified as derangements by the mining engineers of the Office Cherifian Phosphate Group (OCP). Their presence in the phosphatic layers causes two kinds of problems: (1) since the whole phosphatic sequence is overlain by a Quaternary cover, we do not know their volume proportion in the phosphatic layers, and therefore the reserves estimations can be wrong (2) they are g…
Zemes dzīļu bagātības Latvijā: ĢIPŠAKMENS
2020
Buklets "Zemes dzīļu bagātības Latvijā: ĢIPŠAKMENS" iepazīstina ar vienu no Latvijas vērtīgākajiem un perspektīvākajiem dabas resursiem, tā daudzveidīgajiem paveidiem. Iekļauta informācija par ģipšakmens atklāšanas vēsturi, mūsdienās nozīmīgākajām pētītajām atradnēm. Bukletu ilustrē Latvijas Universitātes Muzeja Ģeoloģijas kolekciju ģipšakmens paraugu fotogrāfijas.