Epigenetic - Cavity Filling Process a Genetic Model of Barytess Deposits of Rajgarh, District Alwar (Rajasthan) |

ABSTRACT:

Present study has been confined to Rajgarh belt ofDistrict Alwar (Rajasthan).  Specimens ofBarytess and host rock were collected from this area for the purpose of study.Barytess (BaSO­₄) is the principalbarium mineral of commerce containing 65.7% BaO and 34.3 % SO₃ with specific gravity of 4.5. In earth crust the bariumvalue varies from 300 to 500 ppm in igneous rocks, basalt contains 100 ppmbarium, granites contain 700 to 800 ppm, syenites and more potassic igneousrocks contain as much as 3000 to 5000 ppm. Barium is too large in ionic radii(1.34 A) and only major element of compare able ionic size with K+(1.33A). There for normally in bistite and potash felspar barium can substitutefor potassium. Hydrothermal solution may extract barium from varioustypes of rocks and the solutions are enriched in barium as compared to potassium.The sulphides of barium are soluble in water and easily transportable. Bariumis there for mobilized, transported and concentrated under the differentconditions. The chemical model of precipitation of berytes of Rajgarh areashows a series of oxidation- rduction reactions. Sulphides in country rocks andadjoining area is considered to be oxidation to form reduced sulphates. Thesulphates percolates downward with meteoric water and combine with bariumbearing brines like BaCL₂, Ba F₂, and Ba CO₃. During themigration of ascending magmatic emanations and hydrothermal solution bariumbearing brins combine with the sulphate to precipitate the barytess. Theprecipitating mineralizing solution was travelled upward through the majorNNE-SSW Trending fault between Aravalli and Delhi and deposited along crossjoint at places along bedding foliation planes.