MINERALS FOUND IN GOA

The State of Goa is endowed with Mineral Resources. Iron

 ore, Manganese ore, Bauxite are minerals of economic importance. Besides there are minor minerals like Basalt, Laterite stones and Rubbles, River sand, Murrum etc., which are in great demand as construction material.

1. Iron ore

Iron ores are rocks and minerals from which metallic iron can be economically extracted. The ores are usually rich in iron oxides and vary in colour from dark grey, bright yellow, or deep purple to rusty red. The iron is usually found in the form of magnetite, hematite, goethite, limonite or siderite. Ores containing very high quantities of hematite or magnetite are known as "natural ore" or "direct shipping ore", meaning they can be fed directly into iron-making blast furnaces

 

2. Manganese ore

Manganese is a chemical element with symbol Mn and atomic number 25. It is not found as a free element in nature; it is often found in minerals in combination with iron. Manganese is a metal with important industrial metal alloy uses, particularly in stainless steels .Historically, manganese is named for pyrolusite and other black minerals from the region of Magnesia in Greece, which also gave its name to magnesium and the iron ore magnetite .

   

3.Bauxite

Bauxite is a sedimentary rock with a relatively high aluminium content. It is the world's main source of aluminium . Bauxite consists mostly of the aluminium minerals gibbsite (Al(OH)₃), boehmite (γ-AlO(OH)) and diaspore (α-AlO(OH)), mixed with the two iron oxides goethite and haematite, the aluminium clay mineral kaolinite and small amounts of anatase (TiO₂) and ilmenite (FeTiO₃ or FeO.TiO₂)

4.Limestone

Limestone is a carbonate sedimentary rock that is often composed of the skeletal fragments of marine organisms such as coral, foraminifera, and molluscs. Its major materials are the minerals calcite and aragonite, which are different crystal forms of calcium carbonate (CaCO₃). A closely related rock is dolostone, which contains a high percentage of the mineral dolomite, CaMg(CO₃)₂. In fact, in old USGS publications, dolostone was referred to as magnesian limestone, a term now reserved for magnesium-deficient dolostones or magnesium-rich limestones. Travertine limestone terraces of Pamukkale, Turkey. About 10% of sedimentary rocks are limestones. The solubility of limestone in water and weak acid solutions leads to karst landscapes, in which water erodes the limestone over thousands to millions of years. Most cave systems are through limestone bedrock Limestone has numerous uses: as a building material, an essential component of concrete (Portland cement),as aggregate for the base of roads, as white pigment or filler in products such as toothpaste      

 

5.Basalt

Basalt is defined by its mineral content and texture, and physical descriptions without mineralogical context may be unreliable in some circumstances. Basalt is usually grey to black in colour, but rapidly weathers to brown or rust-red due to oxidation of its mafic (iron-rich) minerals into hematite and other iron oxides and hydroxides. Although usually characterized as "dark", basaltic rocks exhibit a wide range of shading due to regional geochemical processes. Due to weathering or high concentrations of plagioclase, some basalts can be quite light-coloured, superficially resembling andesite to untrained eyes. Basalt has a fine-grained mineral texture due to the molten rock cooling too quickly for large mineral crystals to grow; it is often porphyritic, containing larger crystals (phenocrysts) formed prior to the extrusion that brought the magma to the surface, embedded in a finer-grained matrix. These phenocrysts usually are of olivine or a calcium-rich plagioclase, which have the highest melting temperatures of the typical minerals that can crystallize from  melting temperatures  of the typical minerals that can crystallize from melting temperatures of the typical minerals

   

Source:-Wikipedia

Date:-9 march 2019