China
Africa
Explore chapters and articles related to this topic
The Forcarei Norte and Lalín pegmatite fields, Galicia, Northwest of Spain
Published in Adam Piestrzyński, Mineral Deposits at the Beginning of the 21st Century, 2001
M. Fuertes-Fuente, A. Martin-Izard
Group L2. Albite pegmatites. These outcrop as dykes and as ellipsoidal to subrounded bodies. Their main characteristic is a banded structure in which three different types of bands alternate and are parallel to the host-rock contact. These bands have been named quartz-muscovite, granitic albite-rich and aplitic albite-rich. The muscovite-quartz bands are always present in the pegmatitic border. The granitic albite-rich bands are made up of albite, quartz, muscovite and K-feldspar along with beryl, garnet (51.5%Alm., 48 %Sps., 0.5 %Grs.), columbitetantalite and phosphates as accessory minerals. Their texture is granitic. However, isolated perthitic K-feldspar with comb-texture growing at right angles to the bands also occurs. The phosphates are fluorapatite, eosphorite-childrenite, hydroxyl-herderite, montebrasite and probable xanthoxenite (from EMA). Eosphorite-childrenite and montebrasite often appear together as patches replacing albite. Xanthoxenite and fluorapatite fill cavities. Hydroxyl-herderite along with Mn-rich apatite occur in veinlets which crosscut the whole pegmatite body. The aplitic albite-rich bands are mainly formed by saccharoidal albite. The main accessory minerals are columbite-tantalite and zircon These bands are the richest in columbite-tantalite.
Assessing groundwater quality and health risks of fluoride pollution in the Shasler Vagu (SV) watershed of Nalgonda, India
Published in Human and Ecological Risk Assessment: An International Journal, 2020
Narsimha Adimalla, Sudheer Kumar Marsetty, Panpan Xu
Fluoride contamination in groundwater is one of the widespread problem in the arid and semi-arid regions of the world and millions of populace suffering from the endemic fluorosis due to consumption of high fluoride drinking water. Typically, fluoride enters into the groundwater both geogenic and anthropogenic sources, in which large contribution is from geogenic source. Several studies have revealed that areas with fluoride contamination in groundwater are typically characterized by the hard rocks/granites which can highly be consisted of fluoride bearing minerals such as fluorite (CaF2), fluorapatite [Ca5(PO4)3(Cl,F,OH)], cryolite (Na3AlF6), villiaumite (NaF), lepidolite KLi(Fe,Mg)Al(AlSi4O10)(F,OH), muscovite (KAl2(AlSi3O10)(OH,F)2, hornblende NaCa2 (Mg,Fe,Al)5(Si,Al)8O22(OH,F)2, herderite Ca(BePO4)(F,OH), holmquistite Li2(Mg,Fe2+)3(Al,Fe3+)2(Si2O22)(OH,F)2, topaz (Al2(F,OH)SiO4), wohlerite NaCa2(Zr,Nb)O(Si2,O7)F, topaz Al2SiO4(OH,F)2, arfvedsonite (Na3Fe42+Fe3+(Si4O11)2(OH,F)2, tainiolite (KLiMg2(Si4O10)F2, polylithionite (KLi2Al(Si4O10)(F,OH)2, microlite (Ca,Na)2Ta2O6(O,OH,F), pyrochlore (NaCaNb2O5F), bastnasite (CeCO3F), gagrinite (NaCaYF6), fluocerite (CeF3), synchisite CeCa(CO3)2F, parisite (Ce2Ca(CO3)3F2 etc. (Adimalla and Venkatayogi 2017; Apambire et al. 1997; Ayoob and Gupta 2006; Chatterjee et al. 2017; Jacks et al. 2005; Machender et al. 2014; Narsimha and Rajitha 2018; Saxena and Ahmed 2003; Subba Rao 2017; Sudheer Kumar et al. 2017), these minerals largely influence the groundwater chemistry, and also progressively enhance the concentration of fluoride in the groundwater by various chemical process. However, in the world 25 nations, including, India, Pakistan, China, Mexico, Korea, and Japan are at very high risk of fluorosis, and also more than 200 million people suffering from the deadly disease of “fluorosis” (Adimalla et al. 2018c; Ali et al. 2016; Ayoob and Gupta 2006; Brindha et al. 2011; Chen et al. 2019; Edmunds and Smedley 2013; Narsimha and Sudarshan 2017a; Subba Rao 2017).