Geology Essay Example | Topics and Well Written Essays - 250 words - 8

Geology - Essay Example The calcites are usually transparent or opaque and have traces of phosphorescence and/or fluorescence hence when used to view objects, they appear double. This is why its use for optical purposes. It occurs naturally owing to the marine decomposition of hard planktons like red algae, echinoderms, and sponges and it is found in limestone, volcanic, kimberlites, sedimentary or peridotites. It is used especially in military for in gun sights .It has also agricultural uses like stabilization of soil and concrete repair. Marcasite or white iron pyrite is a product of iron (Fe) and sulphur (s), to form Iron sulfide (Fes3). It has black metallic appearance and changes to brown or yellowish color. Its occurrence is primary or secondary in nature. Primarily, it occurs in highly acidic and with low temperatures conditions, mainly on sedimentary rocks or hydrothermal veins. In secondary, it is formed on alteration of chemicals of a parent mineral such as chalcopyrite. It reacts in high humidity to form iron (II) suphate and sulphuric acid. It is used mainly used for ornamental purposes and a source of sulphur. Galena is the natural form of the mineral lead sulphide and is the main ore for both silver and lead. It is also called lead glances and distributed widely on the sulphide minerals. It is mainly used to make lead- acid batteries, lead sheets and