QE460 : Geology, genesis, industrial properties and enhancement of Ferdows agates
Thesis > Central Library of Shahrood University > Geosciences > MSc > 2019
Authors:
Abstarct: The Ferdows agates, located at 120 km NW Birjand, are parts of Central Iranian (Lut block). Silica mineralization (Agate) occurred in Eocene-Oligocene volcanic units such as basalt, andesite, basaltic andesite and pyroclastic rocks (tuff and lithic tuff) with two major structures including vein and filling cavities. The agates can be oberserved in different shape and pattern such as moss, dendritic, concentric, laxyered, tabular, cauliflower that are white, green, yellow, black, red and gray in colors. Petroghraphy observations and Raman spectroscopy revealed that the agate of Ferdows was composed mainly of chalcedony, moganite and quartzine, and calcite are the only minor mineral observed in them. As most of the study agates area are white and colorless, the variety of chemical solutions (such as cobalt chloride hexahydrate, copper chloride, iron nitrate, potassium chromate and nitrate Copper), gamma-ray and heating techniques were used to to enhance their quality and economic value. The results show that these metods had little effect on their quality. The Ferdows agates have SiO2= 95.78 to 98.9 wt% with minor value of CaO, Fe2O3, Al2O3 and Na2O. They show a slight negative slope in the normalized chondrite and primitive mantle diagrams and their trace elements are lower than the host volcanic rocks. The abundance of U is equal to or even higher in red agate than in host rocks. This is due to the release of the Si and U elements due to the alteration of the host rocks, followed by the conversion of U to uranyl ions and the formation of bonds with the surface of silica tetraers. Similarities in the trace elements designs of volcanic agates and rocks indicate that these elements are mobilized by fluid circulation during late- or post-volcanic altration activity.
Keywords:
#Geochemistry #Raman spectroscopy #Agate #Ferdows #South Khorasan #Central Iran. Link
Keeping place: Central Library of Shahrood University
Visitor:
Keeping place: Central Library of Shahrood University
Visitor: